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  • 1995-1999  (373)
  • 1997  (373)
  • Analytical Chemistry and Spectroscopy  (212)
  • crystal structure  (134)
  • Atomic, Molecular and Optical Physics
  • Nuclear reactions
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Years
  • 1995-1999  (373)
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Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Synthesis and Characterization of the Isocyanide Ligated Centered Zirconium Halide Cluster [(Zr6Be)Cl12(CNXyl)6] (1997)
    Springer
    Journal of cluster science 8 (1997), S. 521-531 
    Details
    ISSN: 1572-8862
    Keywords: Zirconium clusters ; isocyanide ; synthesis ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The first isocyanide ligated hexanuclear zirconium halide cluster is reported. The unoxidized [(Zr6Be)Cl12(CNXyl)6] (CNXyl = 2,6-dimethylphenyl isocyanide) was obtained from the solid state precursor K3Zr6Cl15Be by dissolution in CH3CN in the presence of CNXyl. The CNXyl ligands occupy all the axial positions on the cluster. The compound was recrystallized from CH2Cl2 and Et2O. [(Zr6Be)Cl12(CNXyl)6].2CH2Cl2 crystallizes in the space group $${\text{P}}\overline {\text{1}} $$ (#2) with a = 12.092(5) Å, b=12.728(5) Å, c = 14.102(8) Å, α = 104.98(4)°, β =107.11°, γ = 100.94°, V = 1919(2) Å3, Z = l, R = 11.3% and R W = 27.0%. For the bound isocyanide ligands, v CN increases to 2140 cm−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022605113866
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  • 2
    Electronic Resource
    Electronic Resource
    Reactions of the Dirhenium(II) Complexes Re2 X 4(μ-dppm)2 (X=Cl, Br; dppm=Ph2PCH2PPh2) with Isocyanides. Part XV: A Fifth Structural Isomer of the [Re2Cl3(μ-dppm)2(CO)(CNXyl)2]+ Cation (Xyl = 2, 6-Dimethylphenyl) (1997)
    Springer
    Journal of cluster science 8 (1997), S. 547-551 
    Details
    ISSN: 1572-8862
    Keywords: Rhenium ; dirhenium complexes ; rhenium–rhenium multiple bonds ; isocyanide ligands ; carbonyl ligand ; structural isomers ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The reaction of the unsymmetrical, coordinatively unsaturated dirhenium(II) complex [(XylNC)(OC)CIRe(μ-dppm)2ReCl2]O3SCF3 (dppm = Ph2PCH2PPh2) with one equivalent of XylNC in CH2Cl2 affords a fifth structural isomer of the [Re2Cl3(μ-dppm)2(CO)(CNXyl)2] + cation; this is believed to have a CO-bridged structure of the type [(XylNC)ClRe(μ-Cl)(μ-CO)(μ-dppm)2ReCl(CNXyl)]+. The latter complex reacts with a further equivalent of XylNC in the presence of Tl+ to form the [Re2Cl2(μ-dppm)2(CO)(CNXyl)3]2+ cation, which has been shown by IR spectroscopy, and by the X-ray crystallographic characterization of its neutral congener Re2Cl2(μ-dppm)2(CO)(CNXyl)3, to contain a very weak and unsymmetrical CO bridge.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022609214775
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  • 3
    Electronic Resource
    Electronic Resource
    Thermal latent coordination compounds (1997)
    Springer
    Journal of thermal analysis and calorimetry 50 (1997), S. 569-586 
    Details
    ISSN: 1572-8943
    Keywords: crystal structure ; metal(II) picolinate and quinaldinate ; thermal degradation of imidazole and pyrazole complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Complexes of the type M(Pa)2(HAz)2 and M(QA)2(HAz)2 (M=cobalt(II) and nickel(II); HPa=picolinic acid, HQa=quinaldic acid; HAz=azoles like imidazole (Him), pyrazole (HPz), benzimidazole (HBzIm) etc.) show a similar thermal behaviour. In the first step of decomposition the corresponding azolinium picolinates or quinaldinates (H2AzPa, H2AzQa) are split off with formation of polymeric mixed ligand complexes M(Pa)(Az) or M(Qa)(Az). X-ray analysis of Co(Qa)2(HBzIm)2 XIIIa illustrates a proton transfer and a subsequent thermal removal of benzimidazolinium quinaldinate (H2BzImQa): Hydrogen bridges from pyrrole nitrogen of the benzimidazole to the non-coordinated oxygen of the quinaldinate predetermine the thermal initiated proton transfer. The high volatility of the heterocyclic acids and the nitrogen coordination are responsible for the formation of the mixed ligand complex Co(Qa)(BzIm) XIVa. Exceptions are the complexes M(Pa)2(HPz)2 XIa-b and M(Qa)2(HIm)2 XVIIa-b. Pyrazole is eliminated from the complexes XIa-b with formation of the solvent-free inner complex M(Pa)2 XIIa-b. From compounds XVIIIa-b quinaldic acid or their decomposition products are split off and a high temperature modification of M(Im)2 XVIIIa-b is formed at elevated temperature. XVIIIa-b are decomposed to the cyanides M(CN)2 similarly to the thermal behaviour of Cu(Im). In the first step the thermal degradation of imidazole and pyrazole adducts of copper(II) picolinates and quinaldinates is characterized by the elimination of azoles. The reason for this thermal behaviour is the weaker coordination of the azole heterocycles in copper chelate compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01979029
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  • 4
    Electronic Resource
    Electronic Resource
    Structures and tautomeric interconversions of anthraquinone imine derivatives (1997)
    Springer
    Structural chemistry 8 (1997), S. 197-204 
    Details
    ISSN: 1572-9001
    Keywords: Tautomerism ; anthraquinone ; crystal structure ; semiempirical computations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Substituted 1-hydroxy-9,10-anthraquinone-9-imines have been found to exhibit tautomeric interconversions between the 9,10- and 1,10-quinonoid forms in the solid state as well as in solution. Single-crystal X-ray crystallography was used to study the structures of 4-(N-acetyl-p-tolylamino)-9-amino-1,10-anthracenedione and 4-hydroxy-1-phenylamino-10-mesitylimino-9(10H)-anthracenone at ambient and low temperatures. The former compound gave crystals belonging to the monoclinic space group P2l/c and, at 295 K,a=9.684(2),b=16.371(3),c=12.097(2) å,Β=110.41(1)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02263507
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis and structure of 5-methoxy-4-methylbenzopsoralen (1997)
    Springer
    Structural chemistry 8 (1997), S. 453-457 
    Details
    ISSN: 1572-9001
    Keywords: Benzopsoralen ; photochemotherapeutic agent ; crystal structure ; molecular mechanics ; AM1 theoretical calculations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract 5-Methoxy-4-methyl-2H-benzofuro[3,2-g]benzo-1-pyran-2-one was synthesized and its crystal structure was determined and compared with the optimal conformation arrived at by MM and AM1 theoretical calculations. The latter indicated that the tetracyclic skeleton is planar with total length (C2–C8) 9.23 å, and that the line joining the conters of the terminal-benzene and furan rings makes an angle of 30.5
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311704
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  • 6
    Electronic Resource
    Electronic Resource
    The crystal and molecular structures of cellulose I and II (1997)
    Springer
    Glycoconjugate journal 14 (1997), S. 677-690 
    Details
    ISSN: 1573-4986
    Keywords: molecular dynamics ; crystal structure ; cellulose I and II
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The paper describes molecular dynamics (MD) simulations on the crystal structures of the Iβ and II phases of cellulose. Structural proposals for each of these were made in the 1970s on the basis of X-ray diffraction data. However, due to the limited resolution of these data some controversies remained and details on hydrogen bonding could not be directly obtained. In contrast to structure factor amplitudes in X-ray diffraction, energies, as obtained from MD simulations, are very sensitive to the positions of the hydroxyl hydrogen atoms. Therefore the latter technique is very suitable for obtaining such structural details. MD simulations of the Iβ phase clearly shows preference for one of the two possible models in which the chains are packed in a parallel orientation. Only the parallel-down mode (in the definition of Gardner and Blackwell (1974) J Biopolym 13: 1975-2001) presents a stable structure. The hydrogen bonding consists of two intramolecular hydrogen bonds parallel to the glycosidic linkage for both chains, and two intralayer hydrogen bonds. The layers are packed hydrophobically. All hydroxymethyl group are positioned in the tg conformation. For the cellulose II form it was found that, in contrast to what seemed to emerge from the X-ray fibre diffraction data, both independent chains had the gt conformation. This idea already existed because of elastic moduli calculations and 13C-solid state NMR data. Recently, the structure of cellotetraose was determined. There appear to be a striking similarity between the structure obtained from the MD simulations and this cellotetraose structure in terms of packing of the two independent molecules, the hydrogen bonding network and the conformations of the hydroxymethyl group, which were also gt for both molecules. The structure forms a 3D hydrogen bonded network, and the contribution from electrostatics to the packing is more pronounced than in case of the Iβ structure. In contrast to what is expected, in view of the irreversible transition of the cellulose I to II form, the energies of the Iβ form is found to be lower than that of II by 1 kcal mol-1 per cellobiose.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018509231331
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  • 7
    Electronic Resource
    Electronic Resource
    The molecular complex of dibenz[a,c]anthracene and trinitrobenzene (1997)
    Springer
    Structural chemistry 8 (1997), S. 141-147 
    Details
    ISSN: 1572-9001
    Keywords: Dibenzanthracene ; trinitrobenzene complex ; trinitrobenzene complex ; π-complex ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The crystal structure of the complex between the polycyclic aromatic hydrocarbon di-benz[a,c]anthracene and 1,3,5-trinitrobenzene is reported. The crystals are triclinic, space group P¯1 with unit cell dimensionsa=7.277(2) å,b=11.237(6) å, andc=13.902(5) å,α= 104.13(4)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02262849
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  • 8
    Electronic Resource
    Electronic Resource
    Large differences are observed between the crystal and solution quaternary structures of allosteric aspartate transcarbamylase in the R state (1997)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 27 (1997), S. 110-117 
    Details
    ISSN: 0887-3585
    Keywords: small-angle scattering ; x-rays ; allosteric enzymes ; crystal structure ; rigid body modeling ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Solution scattering curves evaluated from the crystal structures of the T and R states of the allosteric enzyme aspartate transcarbamylase from Escherichia coli were compared with the experimental x-ray scattering patterns. Whereas the scattering from the crystal structure of the T state agrees with the experiment, large deviations reflecting a significant difference between the quaternary structures in the crystal and in solution are observed for the R state. The experimental curve of the R state was fitted by rigid body movements of the subunits in the crystal R structure which displace the latter further away from the T structure along the reaction coordinates of the T→R transition observed in the crystals. Taking the crystal R structure as a reference, it was found that in solution the distance between the catalytic trimers along the threefold axis is 0.34 nm larger and the trimers are rotated by 11° in opposite directions around the same axis; each of the three regulatory dimers is rotated by 9° around the corresponding twofold axis and displaced by 0.14 nm away from the molecular center along this axis. Proteins 27:110-117 © 1997 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Bactericidal antibody recognition of a PorA epitope of Neisseria meningitidis: Crystal structure of a Fab fragment in complex with a fluorescein-conjugated peptide (1997)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 29 (1997), S. 113-125 
    Details
    ISSN: 0887-3585
    Keywords: bactericidal antibody ; crystal structure ; Neisseria meningitidis ; peptide-fluorescein conjugate ; PorA outer membrane protein ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Class 1 outer membrane protein PorA of Neisseria meningitidis is a vaccine candidate against bacterial meningitis. Antibodies against PorA are able to induce complement-mediated bacterial killing and thereby play an important role in protection against meningococcal disease. Bactericidal antibodies are all directed against variable regions VR1 and VR2 of the PorA sequence, corresponding to loops 1 and 4 of a two-dimensional topology model of the porin with eight extracellular loops. We have determined the crystal structure to 2.6 Å resolution of the Fab fragment of bactericidal antibody MN12H2 against meningococcal PorA in complex with a linear fluorescein-conjugated peptide TKDTNNNL derived from the VR2 sequence of sero-subtype P1.7,16 (residues 180-187) from meningococcal strain H44/76. The peptide folds deeply into the binding cavity of the Fab molecule in a type I β-turn, with the minimal P1.16 epitope DTNNN virtually completely buried. The structure reveals H-bonds and van der Waals interactions with all minimal epitope residues and one essential salt bridge between Asp-182 of the peptide and His-31 of the MN12H2 light chain. The key components of the recognition of PorA epitope P1.16 by bactericidal antibody MN12H2 correspond well with available thermodynamic data from binding studies. Furthermore, they indicate the structural basis of an increased endemic incidence of infection by group B meningococci in England and Wales since 1981 associated with the occurrence of an Neisseria meningitidis escape mutant (strain MC58). The observed three-dimensional conformation of the peptide provides a rationale for the development of a synthetic peptide vaccine against meningococcal disease. Proteins 29:113-125, 1997. © 1997 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Computational, pulse-radiolytic, and structural investigations of lysine-136 and its role in the electrostatic triad of human C u,Z n superoxide dismutase (1997)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 29 (1997), S. 103-112 
    Details
    ISSN: 0887-3585
    Keywords: Brownian dynamics ; molecular recognition ; site-directed mutagenesis ; facilitated diffusion ; crystal structure ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Key charged residues in Cu,Zn superoxide dismutase (Cu,Zn SOD) promote electrostatic steering of the superoxide substrate to the active site Cu ion, resulting in dismutation of superoxide to oxygen and hydrogen peroxide. Lys-136, along with the adjacent residues Glu-132 and Glu-133, forms a proposed electrostatic triad contributing to substrate recognition. Human Cu,Zn SODs with single-site replacements of Lys-136 by Arg, Ala, Gln, or Glu or with a triple-site substitution (Glu-132 and Glu-133 to Gln and Lys-136 to Ala) were made to test hypotheses regarding contributions of these residues to Cu,Zn SOD activity. The structural effects of these mutations were modeled computationally and validated by the X-ray crystallographic structure determination of Cu,Zn SOD having the Lys-136-to-Glu replacement. Brownian dynamics simulations and multiple-site titration calculations predicted mutant reaction rates as well as ionic strength and pH effects measured by pulse-radiolytic experiments. Lys-136-to-Glu charge reversal decreased dismutation activity 50% from 2.2 × 109 to 1.2 × 109 M-1 s-1 due to repulsion of negatively charged superoxide, whereas charge-neutralizing substitutions (Lys-136 to Gln or Ala) had a less dramatic influence. In contrast, the triple-mutant Cu,Zn SOD (all three charges in the electrostatic triad neutralized) surprisingly doubled the reaction rate compared with wild-type enzyme but introduced phosphate inhibition. Computational and experimental reaction rates decreased with increasing ionic strength in all of the Lys-136 mutants, with charge reversal having a more pronounced effect than charge neutralization, implying that local electrostatic effects still govern the dismutation rates. Multiple-site titration analysis showed that deprotonation events throughout the enzyme are likely responsible for the gradual decrease in SOD activity above pH 9.5 and predicted a pKa value of 11.7 for Lys-136. Overall, Lys-136 and Glu-132 make comparable contributions to substrate recognition but are less critical to enzyme function than Arg-143, which is both mechanistically and electrostatically essential. Thus, the sequence-conserved residues of this electrostatic triad are evidently important solely for their electrostatic properties, which maintain the high catalytic rate and turnover of Cu,Zn SOD while simultaneously providing specificity by selecting against binding by other anions. Proteins 29:103-112, 1997. © 1997 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
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  • 11
    Electronic Resource
    Electronic Resource
    The crystal structure of 1,4-benzenedithiol by rietveld analysis and studies on the mechanism of solid-state addition polymerization of 1,4-benzenedithiol to 1,4-diethynylbenzene (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 1621-1625 
    Details
    ISSN: 0887-624X
    Keywords: 1,4-benzenedithiol ; 1,4-diethynylbenzene ; crystal structure ; solid-state polymerization ; layer structure ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structure of 1,4-benzenedithiol (BDT) was determined by the Rietveld method based on the calculation of the atomic coordinates of the BDT molecule using the Molecular Mechanics Program (MMP2). The refined crystal structure of BDT was monoclinic P21/c with dimensions, a = 7.795, b = 7.290, c = 5.955 Å, β = 92.16°, z = 2. The R factor of the refined structure was 0.038. Using above results, the mechanism of solid-state addition polymerization of BDT to 1,4-diethynylbenzene (DEB) was studied. Sublimed BDT piles up onto glass plate substrate and forms the layer structure along with the a axis. An inclination angle of the piled BDT column was 60° toward the substrate surface. DEB crystal structure was also monoclinic P21/c with a = 4.007, b = 6.018; c = 15.340 Å, β = 91.42°, z = 2. Sublimation of equimolar mixture of BDT and DEB gave a crystal having 1 : 1 composition, in which DEB column is situated between the columns of BDT. Relative arrangement of both monomers was suitable for the addition of —SH and —C=CH groups, since the distance between the two groups is 3.3 Å by CERIUS II calculation. Therefore, the addition polymerization of BDT to DEB easily proceeded by UV irradiation and the resulting polymer had a highly layer structure along with the a axis of BDT crystal. Tentatively estimated crystal structure of polymer obtained is monoclinic with a = 7.73, b = 7.30, c = 5.95 Å, β = 92.16°. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1621-1625, 1997
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  • 12
    Electronic Resource
    Electronic Resource
    Crystal Structures of 1,3-Calix[4]-bis-crown-6·3CH3CN and 1,3-Calix[4]-bis-(benzo-crown-6)·3 CH3CN (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 27 (1997), S. 169-178 
    Details
    ISSN: 1573-1111
    Keywords: Bridged calix[4]arene ; ditopic receptor ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The crystal structures of a new solvate of the ditopic receptor 1,3-calix[4]-bis-crown-6, Bis-C6, and of 1,3-calix[4]-bis-(benzo-crown-6), Bis-benzoC6, are reported. Bis-C6.3 CH3CN (1) crystallizes in the monoclinic space group P21/n, a = 14.388(3), b = 26.947(8), c = 14.707(4) Å, β = 113.19(3)°, V = 5241(5) Å3, Z = 4. Refinement led to a final conventional R value of 0.092 for 2723 reflections. The structure of (1) differs from the previously reported structure of Bis-C6.4 CH3CN by the conformation of one crown either chain. Two acetonitrile molecules are in the close neighbourhood of the crown ether cavities. Bis-benzoC6.3 CH3CN (2) crystallizes in the monoclinic space group P21/c, a = 10.391(4), b = 17.264(11), c = 30.426(9) Å, β = 94.62(3)°, V = 5440(7) Å3, Z = 4. Refinement led to a final conventional R value of 0.106 for 2965 reflections. Two acetonitrile molecules are located near the crown ether cavities, as in (1). One of the crown ether conformations is the same as in the binuclear caesium complex of Bis-benzoC6, supporting the hypothesis of a preorganization of this ligand towards the complexation of this ion; the second crown ether chain is partially disordered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007990208036
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  • 13
    Electronic Resource
    Electronic Resource
    X-Ray Structure and Proton NMR Study of a Hexacoordinated Lithium Complex (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 28 (1997), S. 125-140 
    Details
    ISSN: 1573-1111
    Keywords: X-ray ; crystal structure ; Li-complex ; triamides ; 1H-NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The structure of the lithium complex with1,3,5-tris[oxymethylene(N,N-dicyclohexyl)carboxyamido]cyclohexanehas been determined by the X-ray method.The compound is triclinic, space group P¯1,a = 15.623(3), b = 19.279(4),c = 19.295(4)Å α = 102.32(3), β = 92.45(3),γ = 105.67(3)0, V = 5436(2)Å3, Z = 4. Itscomposition is represented by the formulaC48H82N3O6LiI 0.5H2O. The lithium cationis encapsulated in a polar pseudo-cavity of six oxygen atoms of the ligandmolecule and displays a distorted trigonal prism coordination. The conformationof the ligand in the solid state complex has been compared with the conformationof the complex in solution determined by 1H-NMR measurements. Supplementary data relevant to this publication have been deposited with the British Library, No. SUP 82224 (21 pages).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007955923966
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  • 14
    Electronic Resource
    Electronic Resource
    Inclusion Compounds of NaI with 13-Membered Azo- and Azoxycrown Ethers (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 28 (1997), S. 17-32 
    Details
    ISSN: 1573-1111
    Keywords: Azocrown ether ; azoxycrown ether ; sodium complexes ; crystal structure ; X-ray analysis ; conformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Sodium iodide complexes of 13-membered azo-(I)and azoxycrown ethers (II) have been synthesized. Compound I[Na(L1 trans)2]⋅I⋅H2O is triclinic witha = 11.53(2), b = 15.74(2), c = 19.17(2) Å,α = 98.93(9), β = 105.51(9),γ = 89.20(9) deg.; Z = 4, space groupP1. Compound II [Na(L2)2]⋅I is orthorhombic witha = 12.451(2), b = 13.796(3), c = 18.667(4)Å; Z = 4, space group P212121. In bothcomplexes the cation is coordinated tochain oxygen atoms and to one nitrogen atom of the azoor azoxy unit. The ability of bothligands to form complexes in relation to thegeometry of the azo or azoxy subunit of themacrocycle is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007929726695
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  • 15
    Electronic Resource
    Electronic Resource
    Polymorphism of Inclusion Complexes and Unsolvated Hosts. II. Structure of the β-Dimorph of the Host-Guest Complex of Dianilinegossypol with Ethylacetate (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 27 (1997), S. 105-112 
    Details
    ISSN: 1573-1111
    Keywords: β-Dimorph ; crystal structure ; dianilinegossypol ethylacetate 1 : 1 clathrate ; packing motifs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Depending on crystallization conditions, dianilinegossypol and ethylacetate form low (ambient temperature, α-phase) and high temperature (t = 35°C, β-phase) clathrate modifications. The structure of the α-phase has been discussed earlier [1]. Crystals of the 1 : 1 β-phase complex, C42H40O6N2·C4O2H8, are monoclinic, space group P21/c, a = 11.362(6), b = 19.479(9), c = 19.085(9) Å, β = 103.21(4)°, V = 4112(3)Å3, Z = 4, R = 0.084 for 3210 observed reflections. In these complexes centrosymmetric dimers of dianilinegossypol molecules formed via O(5)—H···O(3) hydrogen bonds are associated into columns by a weak O(8)—H···O(7) H-bond. A difference in the structure of these two phases is in the packing mode of the columns. The angle formed by intersecting host columns is about 126° for the α-phase and 104° for the β-modification. Guest molecules are hydrogen bonded to the host molecules via an O(1)—H···O(10) bond and are accommodated in channels in α-phase complex and in cavities in β-phase complex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007908530132
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  • 16
    Electronic Resource
    Electronic Resource
    Crystal Structure of a Uranyl/p-tert-Butylcalix[5]arene Complex (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 27 (1997), S. 13-20 
    Details
    ISSN: 1573-1111
    Keywords: Uranyl complexes ; calixarenes ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The synthesis and crystal structure of the inclusion complex between uranyl and p-tert-butylcalix[5]arene are reported. [UO2 (p-tert-butylcalix[5]arene-4H]2- · $${\text{2HNE}}_{{\text{t}}_{\text{3}} }^{\text{ + }} $$ &·2MeOH(1) crystallizes in the monoclinic space group C2/c, a = 30.06(2), b = 18.20(3), c = 31.35(2) Å, β = 128.51(6)°, V = 13423(40) Å3, Z = 8. Refinement led to a final conventional R value of 0.043 for 4155 reflections. The uranyl ion is bonded, in its equatorial plane, to the five oxygen atoms of the calixarene, four of which are deprotonated. A protonated triethylamine molecule is located inside the calixarene cavity and hydrogen bonded to a uranyl oxygen atom, and another one outside and hydrogen bonded to a calixarene oxygen atom. The calixarene conformation is the usual cone one.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007938218723
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  • 17
    Electronic Resource
    Electronic Resource
    Synthesis, Structure and Alkali Metal Ion Binding Properties of a Podand Polyether Derived from Calix[4]arene, 5,11,17,23-tetra-tert-butyl-25,27-di(phenylmethoxy)-26,28-di(2‘-methoxyethoxy)-calix[4]arene (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 27 (1997), S. 291-302 
    Details
    ISSN: 1573-1111
    Keywords: Calix[4]arene ; polyether ; crystal structure ; alkali metal ion binding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The ligand 5,11,17,23-tetra-t-butyl-25,27-di(phenylmethoxy)-26,28-di(2-methoxy-ethoxy)calix[4]arene,designed as an analogue of some calixcrown speciesin order to evaluate possible origins of their selectivity in alkali metal ion binding, has been synthesised and structurally characterised by X-ray crystallography. The crystals are monoclinic, P21/n, a = 15.940(6), b = 19.388(5), c = 20.020(5) Å,β = 109.10(2) deg., Z = 4, conventional R on |F| being 0.073 for 3454 independent, ’observed‘ (I 〉 3σ(I)) reflections. 1H-NMR studies in 1:1 CD3CN/CDCl3solvent have shown that the ligand exerts a strong preference for the lighteralkali metal ions (Li+ and Na+) contrary to the binding behaviour of knowncalixcrowns. This may reflect interactions restricted to the lower rim donor atoms without concomitant interaction with the calixarene π-electrons, perhaps because the latter interactions are substituted by those with the benzyl group π-electrons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007981710765
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  • 18
    Electronic Resource
    Electronic Resource
    Polymorphism of Inclusion Complexes and Unsolvated Hosts. V. Crystal Structure of the α-Dimorph of the 1 : 2 Dianilinegossypol–DMSO Complex and a 1 : 1 : 1 Inclusion Complex Based on a Mixed Dianilinegossypol/1,4-Dioxane Host Matrix and 1,2-Dichloroethane Guest (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 29 (1997), S. 23-32 
    Details
    ISSN: 1573-1111
    Keywords: Dianilinegossypol ; crystal structure ; host–guest complexes ; H-bond ; α- and β-dimorphs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Dianilinegossypol forms a 1 : 2 host-guest complex with DMSO:monoclinic, space group P21/n, a = 8.522(3), b = 18.034(4), c= 28.462(6) Å, β = 94.14(2)°, V = 4362Å3, Z = 4, D x = 1.26 g cm-3, T = 295 K.Final R value is 0.102 for 1793 observed reflections. A 1 : 1 : 1 adduct ofdianilinegossypol with 1,4-dioxane and 1,2-dichloroethane is found to beisostructural with the dianilinegossypol complex with DMSO: monoclinic,space group P21/n, a = 8.281(2), b = 19.245(3), c = 27.970(7)Å, β = 95.18°, V = 4439 Å3, Z = 4, D x =1.28 g cm-3, T = 295 K. Final R value is 0.114 for 2458observed reflections.The host molecules are associated by O(4)—H ...O(3) H-bonds toinfinite chains running in the direction of the c-axis The chains areincorporated into layers through 1,4-dioxane or DMSO molecules havingH-bonds with dianilinegossypol molecules. Another DMSO or 1,2-dichloroethanemolecule is included as a guest in the channels formed between the layers.At 60 °C a cryptate-type inclusion complex of dianilinegossypol isformed with DMSO or 1,4-dioxane. It is isostructural with the acetonecomplex reported in Part IV of the present series.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007992116261
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  • 19
    Electronic Resource
    Electronic Resource
    p-tert-Butylcalix[5]arene: a New Synthetic Pathway and Crystal Structure of the N,N-Dimethylformamide Complex (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 29 (1997), S. 175-185 
    Details
    ISSN: 1573-1111
    Keywords: p-tert-Butylcalix[5]arene ; synthesis ; complexation ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The formation of p-tert-butylcalix[5]arene by the opening ofp-tert-butyldihomooxacalix [4]arene and the addition of a monomer has beenstudied. Various facets, including the effects of bases and the nature ofthe monomer added to the p-tert-butyldihomooxacalix[4]arene, have beeninvestigated. p-tert-Butylcalix[5]arene can be prepared in yields up to30%. The structure of its 1 : 2 complex with DMF has been determinedby X-ray crystallography. Crystals are triclinic, space group P¯1, a =1428.2(3) pm, b = 1837.3(3) pm, c = 1276.1(2) pm, α = 108.98(1)°,β = 105.02(2)°, γ = 95.21(1)°, Z = 2, D c = 1.059 kg m-3,final R value = 0.087. The macrocycle adopts a cone conformation, one guestenclosed inside the cavity, the other one outside.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007907525620
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  • 20
    Electronic Resource
    Electronic Resource
    Synthesis of Two New Glycophanes Comprised of Thioglucose Molecules Linked by Hydrocarbons (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 29 (1997), S. 335-346 
    Details
    ISSN: 1573-1111
    Keywords: Glycophane ; macrocycle ; carbohydrate ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Preparation of two new glycophanes is reported. These compounds arecomprised of two glucose molecules linked by hydrocarbon units at the 1,1′ and 3, 3′ or 3, 3′ and 6, 6′ positions. Thecrystal structure of one of the glycophanes is also described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007952822709
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  • 21
    Electronic Resource
    Electronic Resource
    Determination of polar analytes in aqueous matrices by purge and trap (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 10-16 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Purge and Trap ; Flavors ; Wine ; Polar analytes ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (not readable) fully autimated purge and trap system has been developed for (not readable) detemination of volatile wine components. The proposed system consists of sampler, a purge and trap instrument, and a GC, (not readable) steps, from the uptake of the infiltrated wine from the sampler (not readable) to the printout of the intergrated chromatograms, proceed(not readable), Typical problems occurring when analyzing polar analytes by the classical purse and trap approach have been specifically addressed. The system has been desiggned to handle such difficult (not readable) analytes. Efforts have been made to improve the reproducibility and the carry-over of these analytes. The measures adopted include: thorough rinsing and subsequent conditioning of the P + T parger; elimination of matrix effects by dilution and high salt (not readable); tight specification of purge relevant parameters; split-inter-(not readable) to improve GC retention time reproducibility.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200103
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  • 22
    Electronic Resource
    Electronic Resource
    Modified capillary GC/MS system enabling dynamic headspace sampling with on-line cryofocusing and cold on-column injection of liquid samples (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 24-28 
    Details
    ISSN: 0935-6304
    Keywords: GC-MS ; Headspace sampling ; On-column injection ; No column replacing ; Reversed carrier gas flow ; Honey aroma compounds ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The paper describes a capillary GC/MS hardware arrangement allowong either:(a)on-line injection of sample of gases and vapors coming from dynamic headspace or purg & trap samplers and their subsequent cryofocusing/thermal desorption prior to the analytical capillary column (first column):(b)direct injection of liquid samples through a cold on-column injector into a second analytical column (counted in series with the first).Chromatographic profiles of acacia honey aromas provide condirmation of the suitability of this system.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200105
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  • 23
    Electronic Resource
    Electronic Resource
    Micellar electrokinetic capillary chromatography of algal toxins (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 34-38 
    Details
    ISSN: 0935-6304
    Keywords: Micellar electrokinetic capillary chromatography, MECC ; Algal toxins ; Microcystin LR, YR, RR ; Nodularin ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Recent methods employed for the analysis of algal toxins have focused on high performance liquid chromatography. However these methods suffer from poor resolution, poor efficiency, and long analysis times. This study involves the investigation of a number of toxins including nodularin, microcystin LR, YR, and RR which are cyclic peptides produced by strains of blue-green algae. The electroseparation mode was micellar electrokinetic capillary chromatography (MECC) using a borate buffer containing sodium dodecyl sulfate (SDS) as the surgactant of choice. The method was optimized with standard toxin compounds and employed for the screening opf toxins in supercritical fluid extracts (SFE) of freeze-thawed algal scum samples.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200107
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  • 24
    Electronic Resource
    Electronic Resource
    Comparison of on-column and splitless injection in capillary gas chromatography coupled with atomic emission detection (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 47-49 
    Details
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Atomic emission detection ; On-column injection ; Splitless injection ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200110
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  • 25
    Electronic Resource
    Electronic Resource
    New stationary phases of conjugated π-electron systems for HPLC - characterization of structure and dynamics by solid state NMR spectroscopy (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 39-45 
    Details
    ISSN: 0935-6304
    Keywords: Solud-state NMR spectroscopy ; 1H MAS-only technique ; New stationary phases ; π-π interactions ; Separation of PAH's ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Four new stationary phases for HPLC were prepared by modifying silica gel with a trifrnctional aminoalkyl silane. A conjugated π-electron system was linked to the amino group either directly or with a carboxylic anhydride as a spacer in between. Characterization and dynamic measurements of the new stationary phases were performed by solid state NMR spectroscopy. The results of the 29si and 13C CP/MAS techniques were compared with the recently developed 1H MAS-only technique. Despite strong homonuclear dipole-dipole interactions it was possible to obtain well resolved 1H MAS spectra of those stationaru phases with a high degree of crosslinking. Limited mobility of the aromatic ligand fragments is common for all examined stationaryu phases.The chromatographic properties of the new phases were tested by their ability tio sepatate a mixture of eight PAHS. It could be shown that the π-π interaction mechanism is responsible for the separation of the eight PAHs, because the elution order of the PAHs did not changem despite the use of both a nonpolar mobile phase (n-heptane) and a polar mobile phase (methanol/ water mixture).
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200108
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  • 26
    Electronic Resource
    Electronic Resource
    Masthead (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997) 
    Details
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200201
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  • 27
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    Electronic Resource
    Determination of artemisinin and artemisinic acid by capillary and packed supercritical fluid chromatography (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 62-66 
    Details
    ISSN: 0935-6304
    Keywords: Artemisinin ; Artemisinic acid ; Capillary supercritical fluid chromatography ; Packed supercritical fluid chromatography ; Evaporative light scattering detector ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Artemisinin (an antimalarial compound) and its bioprecursor artemisinic acid, present in the plant Atemisia annua L., were analyzed by supercritical fluid chromatography (SFS) using capillary and packed columns, coupled respectively with a flame ionization detector (FID) and an evaporative light scattering detector (ELSD). Both methods were optimized and validated with columns of different polarity in order to separate artemisinin and artemisinic acid. Analytical results were comparable, but the paced SFC-ELSD method was faster. Indeed, artemisinin and artemisinic acid were separated with an aminopropyl silica column in less than 8 minutes instead of about 25 minutes by capillary SFS. Contrary to conventional gas and liquid chromatography coupled to an UV-visible detector, SFS methods determined both compounds directly, without degradation and/or derivatization in the concentration range expected in the plant material. Results obtained on plant extracts by capillary SFS-FID and packed SFS-ELSD were confirmed by GC-MS.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200203
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  • 28
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    Electronic Resource
    Rapid analysis of unsaturated acidic xylooligosaccharides from kraft pulps using capillary zone electrophoresis (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 72-76 
    Details
    ISSN: 0935-6304
    Keywords: Capillary zone electrophoresis ; Alkaline borate buffer ; UV detection ; Unsaturated acidic xylooligosaccharides ; Alditol derivatives ; 4-Deoxy-L-threo-hex-4-enopyranosyluronic acid ; Hexenuronic acid ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several acidic xylooligosaccharides containing unsaturated “hexenuronic acid” units, i.e. 4-deoxy-L-threo-hex-4-enopyranosy-lurinic acid (4-ΔU) units, were separated as their alditol derivatives by capillary zone electrophoriesis in 438 mM borate buffer (pH 10.3) and were detected selectively at the μM level on-column UV detection at 232 nm. These acidic oligosaccharides were obtained from birch and pine kraft pulps on enzymatic hydrolysis with endoxylanases and subsequent treatment with other Trichoderma reesei enzymes. Under the conditions empolyed, acidic 4-ΔU-containing xylooligosaccharides with a molecular size renging from trisaccharides up to nonasaccharides could be separated. Oligosaccharides with higher molecular mass were detected first. Two 4-ΔU-xylotetraose isomers, with the 4-ΔU-group linked to different xylose units in the iligosaccharide backbone, could be resolved from each other with a resolution of about 1. By using a disaccharide (4-ΔU α-(1 → 4) linked to N-acetyl glucosamine) as a model compound the minimum detectable concentration was determined as 10 μM.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200205
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  • 29
    Electronic Resource
    Electronic Resource
    Characterization and monitoring of amitraz degradation products in honey (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 81-84 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography-atomic emission detection (GC-AED) ; Gas Chromatography-mass spectrometry(GC-MS) ; Amitraz residues ; Hoeny ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Capillary gas chromatography in combination with atomic emission and electron impact-chemical ionizaion mass spectrometry detectors have been used to detect amitraz degradation products in honey storage, characterize their structure, and evaluate their occurrence over a 100 day peroid. To this end, honey samples were extracted with an 8:2 v/v n-hexane/acetone mixture. Amitraz was found to be rapidly decomposed into five related compounds, of which N-(2,4-dimethylphenyl)formamide was the most abundant and persistent.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200207
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  • 30
    Electronic Resource
    Electronic Resource
    Whey proteins eluted reversed phase gradients (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 29-33 
    Details
    ISSN: 0935-6304
    Keywords: LSS model ; Whey proteins ; RP-HPLC of proteins ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The behavior of bovine whey proteins in Reversed-Phase High Performance Liquid Chromatography (RP-HPLC) systems has been investigated. The Linear Solvent Strength (LSS) model has been applied to the separation of these proteins studying how their retention time and band broadening change when different gradient parameters are modified. From our results it is deduced that the LSS model describes the behaviour of the whey proteins in RP-HPLC. Also, it seems that ts (the retention time for non-retained solutes) depends on the size of these proteins. The good fit observed between experimental data and the equations deduced from the LSS model allows the prediction of a gradient shape that permits a rapid analysis of the above mentioned proteins.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200106
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  • 31
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    Gas chromatographic separation of chiral organochlorines on modified cyclodextrin phases and results of marine biota samples (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 85-93 
    Details
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Modified cyclodextrin phases ; Chiral organochlorines ; Biological samples ; Enantiomeric ratios ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Four chiral stationary phases containing modified cyclodextrines diluted in or chemically bonded to a non-chiral phase were used to resolve chiral organochlorine compounds such as α-hexachlorocyclohexane (α-HCH), perdeuterated α-HCH (α-PDHCH), β-and γ-pentachlorocyclohexene (PCCH), oxychlordane, cis-and trans-chlor- dane, cis- and trans-heptachlorepoxide, PCB 95, PCB 132, PCB 149, and Chiral tozaphenes.The elution order was determined by analyzing standards with known enantiomeric excesses.Furthermore, an internal standard was used to even out slight variations in the ratio of peak hights of enantiomers which were determined from injection to injection.None of the chiral stationary phases resolved all chiral organochlorine compounds. However, the β-TBDM(35% heptakis (6-O-t-butyldimethylsilyl-2,3-di-O-methyl)-β-cyclodextrin in OV 1701) column allowed the separation of all compounds under investigation except for PCB 95 and chiral toxaphenes.Emphasis was placed on the separation of as many as possible enantiomers on a chiral phase by application of one temperature program and with respect to unambiguous quantitation of biological samples such as bludder and liver of marine and terrestrial mammals.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200208
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  • 32
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    Electronic Resource
    Troubleshooting in the separation sciences (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 122-122 
    Details
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200214
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  • 33
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    Electronic Resource
    Chromatography calendar (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 123-124 
    Details
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200215
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  • 34
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    Characterization of complex hydrocarbon mixtures using on-line coupling of size-exclusion chromatography and normal-phase liquid chromatography to high-resolution gas chromatography (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 125-130 
    Details
    ISSN: 0935-6304
    Keywords: Size-exclusion Chromatography ; Normal-phase liquid chromatography ; Gas Chromatography Coupled LC-LC ; Coupled LC-GC ; Cleanup and analysis ; Group-type separations ; Automation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An on-line coupling of size-exclusion Chromatography (SEC), normal-phase liquid Chromatography (NPLC), and gas Chromatography (GC) for the characterization of complex hydrocarbon mixtures is described. The hyphenated system separates according to size, polarity, and boiling point. The use of size exclusion as the first separation step allows for the direct injection of complex (“dirty”) samples withont prior clean-up. SEC-NPLC coupling was realized using an on-line solvent evaporator based on fully concurrent solvent evaporation (FCSE) using a modified loop-type interface, vapor exit and co-solvent trapping. Complete reconcentration of the analytes was realized by the introduction of a cryogenic cold trap. For the subsequent hydrocarbon group-type separation an ammo-silica column with n-heptane as eluent was used. The NPLC-GC coupling was based on an on-column interface using partially concurrent solvent evaporation (PCSE) and an early vapor exit. Initial results obtained on the analysis of a residue from the atmospheric crude-oil distillation (a so-called long residue) are presented as an example of the enormous separation power of the SEC-NPLC-GC system. The application of the system for quantitative analysis has not yet been studied.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200302
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  • 35
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    The characterization and quantitation of sulfur-containing compounds in (heavy) middle distillates by LC-GC-FID-SCD (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 131-137 
    Details
    ISSN: 0935-6304
    Keywords: LC-GC hyphenation ; Sulfur chemlluminescence detector ; Organo-sulfur compounds ; Hydrodesulfurizalion ; Middle distillates ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A modified sulfur chemiluniinescence detector (SCO) has been interfaced to a HPLC-HRGC hyphenated system. This combination enables the full characterization and quantitation of the sulfur containing compounds in (heavy) middle distillate oil fractions (boiling range 150-450°C). The system is suited to identify and determine the various groups of orgaiio-sulfur structures such as: thiols + sulfides + thiophencs, benzothiophenes, dibenzothiophenes and benzo-naphthothiophenes. Within these groups a separation according to boiling point is accomplished. Therefore it allows the separation, identification and quantitation of a number of individual species, especially those which are refractory to hydrodesulfu-rization (HDS), such as 3-methyl-benzothiophene, 4-methyl-dibenzothiophene and -J,6-dimethyl-dibenzothiophene. The analysis of these groups and specific compounds is the key in understanding the kinetics of the chemistry involved in HDS. The complete instrumental set-up is fully automated by computer control. To suppress possible interferences and quenching of the sulfur response of the SCL from (large amounts of) hydrocarbons, it is aligned above the adapted flame ionization detector (FID) of the GC. This renders a sensitivity of the SCO for sulfur of 2 pg. s-1, which corresponds to a minimum detectable level for individual sulfur species in oil fractions for the complete system of 1 ppm (mg. kg-1) sulfur. Its linear dynamic range exceeds 105, which means that also untreated, high sulfur containing feedstocks can be analyzed directly. The selectivity of sulfur to carbon of the modified SCO exceeds 106. A number of HDS feedstocks and desulfurized products of different desulfurization levels have been analyzed with the system. From the analysis results the behavior of the refractory compounds in HDS can now be followed closely.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200303
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  • 36
    Electronic Resource
    Electronic Resource
    Standard equivalent chain length values of monoenic and polyenic (methylene interrupted) fatty acids (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 143-158 
    Details
    ISSN: 0935-6304
    Keywords: High resolution gas chromatography ; Column reproducibility ; Equivalent chain length values ; Fatty acid methyl ester analysis ; Capillary columns ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The equivalent chain length (ECL) values of the methyl esters of 83 defined fatty acids (FAs) have been determined by gas chromatog-raphy (GC) on three fused silica DB-WAX and three DB-1 columns. ECL values of further 46 FAs were calculated by different methods. Conditions of chromatography, methods of ECL values calculation and differences between ECL values on individual columns and between trans- and cis-isomers of corresponding FAs are also discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200305
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    Isolation and determination of toxic congeners of polychlorinated biphenyls in environmental samples (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 1-9 
    Details
    ISSN: 0935-6304
    Keywords: GC-MS ; HPLC ; Non-ortho ; mono-ortho ; di-ortho substituted polychlorinated biphenyls (PCBs) ; 2-(1-Pyrenyl)ethyldimethylsilylated silica column ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Method has been developed for the separation and enrichemen of there non-ortho, eight mono-ortho, and di-ortho substituted polychlorinated biphenyls (PCBs) from Aroclor formulations and environmental samples. The fractionation is accomplished using high performance liquid chromatography (HPLC) with a 2-(1-pyrenyl)ethyldimethylsilysily silca column. GC-MSD with an optimized temperature program was used for quantitation, Hexane, pentane, cyclohexane, iso-octane, and 2-propanol were tested as a mobile phase for the isolation of the thirteen target PCBs in a Aroclor 1242, 1254, and 1260 (1:1:1) misture, Pentane at room temperature with a slow rate of 0.7 ml/min is the condition of choice. The average recovery of thirteen target PCBs spiked in the Aroclor mixture is 99.5% with an average relative standard deviation of 4.5%. The average method detection limit is 8pg/μl. Targer PCBs in the reference solis, incinarator ash, and sediment samples were measured.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200102
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  • 38
    Electronic Resource
    Electronic Resource
    Retention tuning in the enantioseparation of naproxen esters and free acid (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 179-180 
    Details
    ISSN: 0935-6304
    Keywords: Enantiomers ; Chiral stationary phase ; Whelk-O ; Coelution ; Peak overlap ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200311
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  • 39
    Electronic Resource
    Electronic Resource
    Simple thermal desorption unit for analysis of volatile organic substances in air samples by GC-MS (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 181-182 
    Details
    ISSN: 0935-6304
    Keywords: HRGC-MS analysis ; Volatile organic compounds ; Thermal desorption ; Air pollution ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200312
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  • 40
    Electronic Resource
    Electronic Resource
    Application of capillary gas chromatography to the determination of ethylene glycol migration from PET bottles in Brazil (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 183-185 
    Details
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Ethylene glycol ; Migration ; Foods or food simulants ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200313
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  • 41
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    Electronic Resource
    Chromatography calendar (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 187-188 
    Details
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200315
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  • 42
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    Electronic Resource
    Maximum transfer condition for spitless injection (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 193-200 
    Details
    ISSN: 0935-6304
    Keywords: Splitless injection ; Vaporizing conditions ; Experimental design ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Splitless injection conditions were optimized by the use of experimental designs (2-level factorial and central composite designs). Modified parameters were: Type of liner, injection volume, solvent, temperature, splitless time. A prolonged splitless time, considered to be an important parameter, proved to be statistically insignificant. This leads to the conclusion that analytes can penetrate the dead volume between column entrance and split valve. To prevent any penetration of solvents, a small reversed split flow was introduced. It could be shown that this auxiliary flow allows an almost complete transfer of solvents. To further speed up the transfer process, a liner modification was proposed.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200403
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  • 43
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    Electronic Resource
    Methodological aspects of headspace SPME: Application of the retention index system (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 217-221 
    Details
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Headspace solid phase microextraction ; Retention index ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The applicability of the retention index system to hcadspacc solid phase microextraxtion (HS-SPME) was investigated. In headspace SPME, the two equilibria gas phase/matrix and fiber coating/gas phase have to he considered. In this paper the equilibrium fiber coating/gas phase is discussed separately to characterize it more detailed and to investigate several methodical aspects. Therefore, the different distribution constants Kfiber/gas of n-alkanes, which were used for reference compounds, were related to their Kováts retention indices. The validity of the derived linear relationship log Kfiber/gas versus retention index I is demonstrated for various examples. This relation is helpful for the assessment of distribution constants of substances not available and for the choice of a suitable fiber coating. Furthermore, quantification of analytes in the gas phase can be done without authentic substances.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200407
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  • 44
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    Determination of organochlorine compounds in fatty matrices: Application of normal-phase LC clean-up coupled on-line to GC/ECD (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 222-226 
    Details
    ISSN: 0935-6304
    Keywords: LC-GC ; Partially concurrent solvent evaporation ; Organochlorines ; PCBs ; Fatty matrices ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Off-line normal-phase LC has been used for the clean-up of compounds in our laboratory for several years. On-line coupling of this LC system, which typically yields 12 ml fractions, is not possible due to its large fraction volume. The maximum transfer volume in on-line LC-GC/ECD is approx. 300 μl. Therefore down-scaling of the LC system was attempted in order to reach these low fraction volumes. Miniaturization resulted in a 240 μ1 LC fraction containing the analytes of interest, which is transferred to GC/ECD via an on-column interface. Sensitivity requires that a minimum amount equivalent to 1-2 mg of sample should reach the GC detector; the selectivity is determined by the separation between the matrix and the last eluting target analyte.For the analysis of fatty samples, limitations were observed in the separation of dieldrin from triglycerides. Other organochlorine compounds, e.g. polychlorobiphenyls (PCBs), the DDT group, HCB and the HCHs can be analyzed with RSDs of 2-4 % (n = 10) at concentration levels of sub-μ/kg in milk fat using a 3 μm Hypersil silica 50 × 1.0 mm i.d. LC column.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200408
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  • 45
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    Electronic Resource
    Supercritical fluid extraction of oxindole alkaloids from Uncaria tormentosa (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 231-236 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography/mass spectrometry (GC/MS) of oxindole alkaloids ; HPLC/MS of oxindole alkaloids ; Supercritical fluid extraction ; Oxindole alkaloids ; Uncaria Tormentosa ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Supercritical fluid extraction of oxindole alkaloids from Uncaria Tormentosa is described. The extraction was performed with supercritical carbon dioxide alone and with supercritical carbon dioxide modified with 10% metanol, and the extracts were analyzed by GC/MS and HPLC/MS.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200410
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  • 46
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    Electronic Resource
    Ion chromatographic determination of salicylate in human serum with a bulk acoustic wave sensor as detector (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 227-230 
    Details
    ISSN: 0935-6304
    Keywords: Ion chromatography ; Bulk Acoustic Wave (BAW) detection ; Salicylate ; Human serum ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Salicylate is a hydrolysis product of salicylate-containing drugs (such as aspirin) in patients' blood. Monitoring of this ion in blood is helpful for diagnosing of overdosage of these drugs. The present paper describes an ion chromatography (IC) method developed for determination of total salicylate in human serum, in which a hulk acoustic wave (BAW) sensor was used as detector; 0.5 mmoI/L sodium carbonate (Na2CO3, pH 8.5) served as mobile phase. Interference in the determination was negligible. The method is simple, rapid, accurate, and precise. Serum salicylate was analyzed using both the proposed IC-BAW method and the classical Trinder spec-trophotometric method, and the results showed that the two method agreed well.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200409
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  • 47
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    Unusual Δ5cis-fatty acids in seed oils of Cimicifuga species (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 237-241 
    Details
    ISSN: 0935-6304
    Keywords: Cimicifuga seed oil ; Δ5-cis fatty acids ; Capillary gas chromatography ; Phylogenetic evolution ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A range of unusual fatty acids with cis-5-unsaturation had been reported in the seed oil of Caltha palustris. Seed oils of Cimicifuga spp. have now been found to contain the same unusual fatty acids as are present in Caltha, plus several other minor fatty acids to give a more complex and more unsaturated seed oil fatty acid pattern.The gas chromatographic fatty acid patterns found seem to be consistent and chemotaxonomically significant, because essentially the same pattern was found in several species of the genus Cimicifuga. These findings may shed a new light on the relation of Cimicifuga to Caltha, and to other genera in the plant family Ranunculaceae.The situation is illustrated by capillary GLC seed oil fatty acid methyl ester “fingerprints” obtained from Cimicifuga and Caltha, and is discussed in relation to other genera. The occurrence in nature of several of these unusual fatty acids, and their chemotax-onomic significance is discussed. The close relation of GLC fatty acid patterns of Caltha and Cimicifuga could indicate monophyly and/or their belonging to the same tribe or subtribe. These observations are not in accordance with the phylogenetic systematic schemes of the genera in this plant family as published by various authors.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200411
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  • 48
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    Simultaneous determination of nicotinamide, nicotinic acid, riboflavin, thiamin, and pyridoxine in enriched Brazilian foods by HPLC (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 245-248 
    Details
    ISSN: 0935-6304
    Keywords: HPLC ; Enriched foods ; Simultaneous determination ; Vitamin analyses ; B-group vitamins ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The control of the enrichment levels in foods is difficult, due mainly to the lack of appropriate analytical methodologies. The amounts of the five B-group vitamins (nicotinamide, nicotinic acid, ribofla-vin, thiamin, and pyridoxine) have been determined in enriched Brazilian foods by a high-performance liquid chromatography (HPLC) method. Fifty products, such as biscuits, liquid and dry milks, flavored milk drinks, flour, macaroni, and cereals were analyzed. Some products showed the amounts declared on the package. Although some slight quantitative variations were shown in the biscuits, one showed levels of riboflavin 35% lower than the value declared. Of five different corn cereal brands, only one showed the declared vitamin content, the others showing levels 30 % lower than that declared. No B-group vitamins were detected in one brand of enriched macaroni, except for the nicotinic acid naturally present in the flour. On the other hand, one flavored milk drink exhibited vitamins levels 200% higher than the amounts declared and one milk drink mix presented thiamin, riboflavin, and nicotinamide levels 3 to 5 times greater than stated. These results suggest an absence of control of the amount of vitamins in enriched foods.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200413
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  • 49
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    Electronic Resource
    Enantiomeric composition of the chiral constituents of essential oils - part 3: Diterpene hydrocarbons (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 257-260 
    Details
    ISSN: 0935-6304
    Keywords: Enantioselective GC ; Diterpene Hydrocarbons ; Cyclodextrin derivatives ; Essential oils ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enantiomeric diterpene hydrocarbons were isolated from different plants and identified by mass spectrometric and NMR investigations. All enantiomeric pairs could be resolved by capillary gas chromatography using either heptakis(2,6-di-O-methyl-3-O-pen-tyl)-β-cyclodextrin or heptakis(6-O-tert-butyldimethylsilyl-2,3-di-O-methyl)-β-cyclodextrin as chiral stationary phases.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200503
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  • 50
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    Electronic Resource
    Determination of inosine 5′-monophosphate and guanosine 5′-monophosphate in pig feed by capillary zone electrophoresis (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 242-244 
    Details
    ISSN: 0935-6304
    Keywords: Capillary zone electrophoresis ; Feed flavor enhancer ; Quantitation ; Inosine 5′-monophosphate ; Guanosine 5′-monophosphate ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A capillary zone clectrophoresis method was developed for the determination of IMP and GIMP, commonly used as flavor enhancers in poultry feed, in a real sample of complex composition. A baseline separation of inosine 5′-monophosphate and guanosine 5′-monophosphate was achieved within 10 min and the other components in the sample did not interfere with the separation. Quantitative results obtained from pig feed samples are presented. The separation conditions and experimental reproducibility are also discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200412
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    Differentiation of strawberry varieties through purge-and-trap HRGC-MS, HRGC-FTIR and principal component analysis (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 275-283 
    Details
    ISSN: 0935-6304
    Keywords: Purge-and-Trap ; GC-FTIR GC-MS ; Aroma Strawberries ; Fragaria anannassa ; Principal components ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The aroma composition of three different Fragaria anannassa cul-tivars Selva, Chandler, and Osso Grande) is studied by purge-and-trap HRGC and the components identified by MRGC-MS and HRGC-FTIR. The chromatographic aroma profiles from four different maturation stages in each variety are compared and the similarities accessed by principal component analysis (PCA). The contents in n-hexanal and hex-2(Z)-enal are characteristic features of the green stage in the three varieties where the content differences in methyl, ethyl, and butyl acetates act as typifying variables among varieties. Ethyl acetate acts as an important differentiation variable for the Selva variety. In the mature stage, the three cultivars may be distinguished from each other through their relative contents of methyl and ethyl 2-methylbutyrate (Selva), methyl 2-methyl-butyrate, methyl butyrate (Chandler), methyl and ethyl butyrates, and methyl caproate (Osso Grande).
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200507
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    Application of capillary electrophoresis in migration studies of food contact materials - part 1: Substituted phenolic additives (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 270-274 
    Details
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis ; Migration ; Substituted phenolic additives ; Antioxidants ; Food contact materials ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method has been developed to determine 11 phenolic antioxidants in the food simulants distilled water, 3% acetie acid, and 15% ethanol, using; micellar capillary electrophoresis (MCE). All the phenols could he analyzed within 35 min. The analytical recovery from spiked simulants was 80 to 119% except for 2,6-di-tert-butyl-4hydroxytoluenc (BHT) and octyl gallate, which could not be recovered from 3% acetic acid simulant. Calibration graph correlation coefficients for the 11 phenols were 0.982 to 0.999. Limits of detection (LoDs) were from 2.8 to 8.6 mg/L. These LoDs are well below European Union migration limits for these substances. It is concluded therefore that MCE offers a rapid and reliable analysis for the control of migration from plastics intended for food contact which employ these phenols as antioxidants.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200506
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    Analysis of individual natural pyrethrins in indoor matrices by HRGC/ECD (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 284-288 
    Details
    ISSN: 0935-6304
    Keywords: HRGC/ECD ; HPLC separation ; 1H-NMR quantitation ; Calibration standards ; Individual components of pyrethrins ; Indoor matrices ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An HRGC/ECD method is presented which permits the identification and quantitation of individual components of pyrethrins (cinerin I, jasmolin I, pyrethrin I, cinerin II, jasmolin II, pyrethrin II) in indoor matrices (airborne particles, house dust) after application of an agent containing pyrethrum. In order to prepare calibration standards for the individual components of the pyrethrum extract, the pyrethrins were isolated hy semi-preparative HPLC and their content and purity were determined by 1H-NMR spectroscopy.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200508
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  • 54
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    Analysis of carbamate pesticides by micellar electrokinetic chromatography (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 265-269 
    Details
    ISSN: 0935-6304
    Keywords: Capillary elcctrophoresis ; Micellar Electrokinetic Chromalography (MEKC) ; Dithiocarbamale(s) ; Thiocarbamate(s) ; Carhamate(s) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Capillary elcctrophoresis (CE) was used for the qualitative and quantitative analysis of eleven compounds of the carbamate, thio-carhamate, and dithiocarbamate classes of pesticides. Micellar elec-trokinetic chromatography (MEKC) was employed for the separation of these substances. The analysis was performed using an uncoated fused silica column, in borate buffer containing SDS and 10% methanol at basic pH, and UV detection at 230 nm. The addition of methanol to the buffer increased the separation and affected intrinsic migration of analytes. The working standard solutions were prepared in acetonitrile/water 50:50. Although these compounds are structurally different, with a large spectrum of chemical properties, such as polarity and solubility, good separation and sensitivity were obtained. Moreover, good recovery of car-bamates was obtained from tap-water using a styrene-divinylben-zene polymer column with the solid phase extraction (SPE) technique.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200505
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    Enantiomeric separation of amphetamine and phenylephrine by capillary zone electrophoresis with hydroxypropyl-β-cyclodextrin as chiral additive (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 298-299 
    Details
    ISSN: 0935-6304
    Keywords: Capillary zone electrophoresis ; Enantiomer separation ; Cyclodextrins ; Amphetamine ; Phenylephrine ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200511
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    Troubleshooting in the separation sciences (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 300-301 
    Details
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200512
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    John G. Dorsey to receive 1997 Benedetti-Pichler award of the American Microchemical Society (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 301-301 
    Details
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200513
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    Masthead (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997) 
    Details
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200601
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    Unusual fatty acids in compositae: γ-Linolenic acid in Saussurea spp. seed oils (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 315-320 
    Details
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Gas chromatography-mass spectrometry ; γ-Linolenic acid ; Saussurea seed oil ; Silver ion TLC ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The plant family Compositae is known to produce a set of unusual fattly acids in their seed oil. Saussurea, a genus of the Compositae is less studied in respect to the fatty acid compsition of their seed oil. Only Saussurea candicans was reported to contain crepenynic acid (33%) as seed oil component.In continuation of our exploration of the portential of wild oil seeds, fatty acids in seed oils of seven Saussurea species (S. amara, S. salicifolia, S. lipschitzii, S. pseudoalpina, S. pricei, S. parviflora, and S. dorogostaiskii) growing in Mongolia a were investigated by means of capillary GLC on capiallary columns of different selectivity (Silar 5 CP and BPX 70).γ-Linolenic acid was found at levels up to 11% of the consitituent fatty acids of Saussurea spp. seed oils. This is the first time that γ-Linolenic acid has been found in members of the plant family Compositae. Moreover, the number, position and configuration of the double bonds in γ-linolenic acid and that of other fatty acids was additionally confirmed by silver ion thin layer chromatography and infrared spectroscopy. The occurence and distribution of γ-linolenic acid, which has found considerable interest for pharmaceutical and dietary use, may be of chemotaxonomical significance in the plant family Compositae.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200604
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    Analysis of volatile sesquiterpenoids in environmental and geological samples (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 305-309 
    Details
    ISSN: 0935-6304
    Keywords: HRGC ; GCMS ; XAD-2 ; Sesquiterpenes ; Sesquiterpenoids ; Volatile lipids ; Biomarkers ; Amazon ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to evaluate vloatile compounds, especiallly sesquiter-penoids, in environmental and geological samples a method was penoids, in environmental and geological samples a method was required to characterize these components when they occur at low concentrations. After fractionation of the total sample extracts by TLC the aliphatic fractions were analyzed by HRGC AND THE kovats indices of all resolved peaks were calculated and comkpared with indices of all resolved peaks were calculated and compared with those obtained for commercial standards. As final step, the fractions were analyzed by HRGC-MS and structures confirmed by comparison of their mass spectra with those of certified sesuiterpene standards. Additionally sesquiterpenoids present in the dissolved phase in water samples were concentrated by solid phase extraction using XAD-2 resin. In this initial study, recovery tests with the resin were carried out in order to evaluate its performance rather than validating the methodology.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200602
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    A continuous liquid-liquid extraction system coupled on-line with capillary gas chromatography for environmental and ecotoxicological analysis (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 325-332 
    Details
    ISSN: 0935-6304
    Keywords: Capillary GC ; Continuous liquid-liquid extraction ; Environmental applications ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The applicability of a liquid-liquid extraction system which is coupled on-line with a capillary gas chromatograph was studied for environmental and ecotoxicological analyses. The optimized and automated system was used for the determination of apolar and rather non-volatile organic compounds in aqueous samples. Relevant aspects of sample introduction, phase separation and selection of extraction solvent are discussed. Three routine-tipe applications are described, viz. an improved method for the determination of hexachlorocyclohexanes in ground water and the determination of the so-called NCC-ether and ACC-ether in ecotoxicological studies. Depending on the application studied, the concentration levels varied from 0.1 to 6000 μg/I, using ECD and/or FID detection. Typical coefficients of variation obtained with the total extraction-GC procedure were 2-25%.The system was found to be rugged, it saves time compared with set-ups involving off-line liquid-liquid extraction and considerably reduces the manual work load.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200606
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    Pressure effects on relative retention in capillary gas-liquid chromatography (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 333-336 
    Details
    ISSN: 0935-6304
    Keywords: Relative retention values ; Pressure effects on relative retention ; Stationary liquid phase ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Equations have been obtained for the dependence of relative retention and retention indexes on average column pressure. The equations suggested conform well with experimental data. It was shown that limiting value of relative retention (at the pressure approaches zero) is an invariant retention value. The nature of the stationary liquid phase used and its film thickness have a substantial influence on the dependence of relative retention and capacity factor on the pressure.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200607
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    Study of the aroma profile of gherkin by purge-and-trap followed by GC-MS (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 343-346 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatographic analysis ; Mass spectrometry ; Purge-and-trap ; Gherkin ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200610
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    Enhanced facilities in digital flowmeters for GC (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 349-349 
    Details
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200613
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    Masthead (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997) 
    Details
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200701
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    Enantiodifferentiation of α-ketols in sherry by one- and two-dimensional HRGC techniques (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 351-354 
    Details
    ISSN: 0935-6304
    Keywords: MDGC ; MCSS ; α-Ketol ; Sherry ; Solerone ; Biogenesis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantiomeric distrubution of solerone (5-oxo-4-hexanolide) 1, ethyl 4-hydroxy- 5-oxohexanoate 2, ethyl 5-hydroxy-4-oxohexanoate 3, 4-oxo-5-hexanolide 4, and solerol (5-hydroxy-4-hexanolide) 5 in sherry wines was determined by several HRGC techniques. While gas chromatography-mass spectrometry on chiral cyclodextrin phases (chiral GC-MS) prevented any racemization of α-ketols 2 and 3 caused by keto-enol tautomerization during analysis, multidimensional gas chromatography MDGC (coupled either by “live-T” switching or by “moving column stream switching” MCSS) led to rearranged constitutional-and stereoisomers. The stereochemical results are discussed regarding the biogenesis of sherry constituents 1-5.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/jhrc.1240200702
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    Analytical approach in diagnosis of inherited metabolic diseases: Maple syrup urine disease (MSUD) - simultaneous analysis of metabolites in urine by enantioselective multidimensional capillary gas chromatography-mass spectrometry (enantio-MDGC-MS) (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 355-362 
    Details
    ISSN: 0935-6304
    Keywords: Enantioselective Multidimensional gas Chromatpgraphy-mass spectrometry (enantio-MDGC-MS) ; Methyl chloroformate (MCF) derivatization ; Inherited metabolic disease ; Maple syrup urine disease (MSUD) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Maple Syrup Urine disease (USUD) is an autosomal recessive inherited metabolic disorder of branched-chain amino acid (L-valin, L-leucine, and L-isoleucine metabolism named after the characteristic smell of affected patients urine. MSUD is caused by a deficiency of the branched-chain α-keto acid dehydrogenase compex resulting in an accumulation of branched-chain aamino acids and the corresponding α-keto-and α-hydroxy acids in blood, urine and cerebrospinal fluid causing neurological damage and mental retardation. The enantioselective analysis of chiral MSUD metabolites and analysis of achiral compounds as corresponding N,O-methoxycarbonyl methyl esters by derivatization with methyl chloroformate (MCF) has been achieved simultaneusly by enantioselective multidimensional gas chromatography-mass spectrometry using heptakis (2,3-di-O-methyl-6-O-tert-butyl-dimethyl-silyl)-β-cyclodextrin as chiral stationary phase. Derivatization with MCF allows the analysis of the structurally different metabolitetes such as branched-chain-carboxylic-, α-oxo-, α-hydroxy- and α-amino acids in a single chromaatographic run. Mass selective detection immensely improves the unequivocaaal identification of metabolites even when they occur as trace compound. The described method allows a reliable screening of MSUD metabolites in patients' urine without time consuming sample preparation and is also suitable for label enrichment analysis without any methodical changes. During this investigation urine sample from three MSUD paatients were analyzed.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/jhrc.1240200703
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    Electrokinetic chromatography using nanometer-sized silica particles as the dynamic stationary phase (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 400-402 
    Details
    ISSN: 0935-6304
    Keywords: Electrokinetic chromatography ; Capillary electrophoresis ; Pseudostationary phase ; Colloidal silica ; Sol ; Uncharged compounds ; Nanoparticles ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200711
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    Application of HPLC-PBMS to the identification of unknown components in a triterpenoid fraction of Arbutus unedo fruits (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 417-420 
    Details
    ISSN: 0935-6304
    Keywords: HPLC-MS ; Particle beam ; HRGC-MS ; Arbutus unedo L. ; Triterpenoids ; Allelopathy ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An extract fraction fruits of Arbutus unedo, L., was cleaned-up by column chromatography and shown by NMR to be a mixture of isomers that resists further attempts at separation by conventional chromatographic methods. High resolution gas chromatography-mass spectrometry (HRGC-MS) confirms the presence of triter-penoid isomers but does not allow separation of all the components. This can be improved by trimethylsilylation but the absence of molecular ions and the complex spectra are difficult to interpret. Complete separation can be achieved by high pressure liquid chro-matography (HPLC) coupled to a mass spectrometer by means of a particle beam interface (HPLC-PBMS). Four triterpene com-pounds are identified through analysis of the corresponding mass spectra: α-amyrin, β-amyrin, and Lupeol, have for the first time been identified in Arbutus unedo, L. Fruits. A new natural triterpene tentatively identified as olean-12-en-3β, 23-diol is described for the first time.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/jhrc.1240200804
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    Reversed phase HPLC coupled on-line to GC by the vaporizer/precolumn solvent split/gas discharge interface; analysis of phthalates in water (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 410-416 
    Details
    ISSN: 0935-6304
    Keywords: Reversed phase LC-GC ; Vaporizer/percolumn solvent split/gas discharge system ; Phthalates in water ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reversed phase liquid chromatography (RPLC) was coupled on-line to gas chromatography (GC) via the vaporizer chamber/preco-lumn solvent split/gas discharge interface outlined recently. Water-containing eluents were driven into a vaporizer chamber at 300°C by the LC pump. The Vapors were removed through an early vapor exist by the carrier gas. Solvent/solute separation occurred in hte retaining precolumn. Special attention was paid to the parame-ters determining the losses of the most volatile compounds. The oven temperature during transfer was lowered close to the dew point of the eluent (the temperature at which recondensation occurs) in order to maximise the retention power of the retaining precolumn. The dew point depends on the transfer rate, the gas flow rate, and the gas inlet pressure. Sometimes even better retention of the vola-tiles was observed at temperatures below the dew point, i.e. despite partial reconsideration. The method was applied to the analysis of phthalates in drinking and surface waters. The detection limits, using MS, were 5-10 ng/l.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200803
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    Identification of migratable substances in recycled high density polyethylene collected from household waste (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 427-430 
    Details
    ISSN: 0935-6304
    Keywords: Gas Chromatography ; High density polyethylene ; Recycled plastics ; Contaminants ; Food packaging ; Migration ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High Density polyethylene regranules reprocessed from separated household waste collection were investigated for migratable con-taminants which were not present in virgin material. Although the material originated from different European reprocessors, the de-tected recycling-specific compounds were similar in most of the investigated samples. At a chosen threshold concentration of 0.5 μg/g more than 70 compounds were tentatively identified. Aroma compounds and preservatives were found in the range of 0.5 to 10 μg/g. Limonene, di(ethylhexyl) phthalate, and the isopropyl esters of myristic and palmitic acids were detected in concentrations up to 200 μg/g. These compounds were found in almost all the regranules. Most of the substances identified are constituents of personal hygiene products and cleaning agents and are therefore absorbed by the package during the storage. Owing to European food legislation and German cosmetics regulations, the use of such recycling packaging material appears suitable only for filling with technical products.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200806
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    SFE of rosemary oil: Assessment of the influence of process variables and extract characterization (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 431-436 
    Details
    ISSN: 0935-6304
    Keywords: Supercritical Fluid Extraction ; High resolution gas chromatography-mass spectrometry ; Volatile compounds ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effects of temperature and solvent density on the characteristics of the extracts obtained from supercritical fluid extraction (SFE) of the volatile compounds from Brazilian rosemary (Rosamarinus officianalis L., Labiatae) using carbon dioxide (CO2) as solvent were investigated. The experiments were performed in a semi-batch laboratory scale home-made unit at two temperatures, viz. 310.15 and 320.15 K, over the pressure range of 100-160 bar. This study allowed to determine the crossover point and the maximum solubility of the oil. The products were analyzed by HRGC-MS, and compounds grouped in three different classes according to their molecular mass distribution in order to evaluate the influence of the variables studied on the characteristics of the extracts. The model proposed by Sovová was adopted in an attempt to interpret the mass transfer phenomena in the extraction process.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200807
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    Full scan GC-MS quantitation of pesticides in spring water at the 10 ppt level using large volume on-column injection (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 447-450 
    Details
    ISSN: 0935-6304
    Keywords: Large Volume cold on-column injection ; Full scan quadrupole mass spectrometry ; Organochlorine and organophosphorus pesticides ; Environmental analyses ; Water ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200810
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    Flow of the carrier gas in open-tubular capillary columns in temperature-programmed gas chromatographyPart of this paper was prsented at the 16th International Symposium on Capillary Chromatography, Riva del Garda, September 27-30, 1994. (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 442-446 
    Details
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Temperature programmed gas chromatography ; Modelling of separation ; Carrier gas flow ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A second-order non-linear partial different equation was derived to describe the dependence of carrier gas pressure in the column on the column distance and the time under temperature programmed conditions. This equation was solved numerically by the modified finite difference method for various column parameters. Constant inlet and outlet pressures were used as boundary conditions. The retention times calculated on assumption of a constant pressure profile along the column. Significant differences between retention times of corresponding solutes calculated by the two methods were found, especially when relatively long columns(L〉50m) with small internal diameter(d〈0.3mm)and high temperature program rates (r〉5°/min)are used.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/jhrc.1240200809
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    Simultaneous determination of purine alkaloids in daily foods by high-performance thin layer chromatography (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 456-458 
    Details
    ISSN: 0935-6304
    Keywords: HPTLC ; Simultaneous determination ; Column extraction ; Purine alkaloids ; Daily foods ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200812
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    Comparison of different heptakis(6-O-alkyldimethylsilyl-2-3-di-O-ethyl)-β-cyclodextrins as chiral stationary phases in capillary GC (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 437-441 
    Details
    ISSN: 0935-6304
    Keywords: Capillary GC ; Enantiomer resolution ; Chiral stationary phase ; Derivated cyclodextrins ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three new β-cyclodextrin derivatives, heptakis(6-O-isopropyldi-methylsilyl-2,3-di-O-ethyl)-β-cyclodextrin, heptakis(6-O-thexyldi-methylsilyl-2,3-di-O-ethyl)-β-cyclodextrin, and heptakis(6-O-cy-clohexyldimethyl-2,3-di-O-ethyl)-β-cyclodextrin (IPDE-β-CD, TXDE-β-CD, and CHDE-β-CD), were synthesized and the enan-tioselectivities of these three CD derivatives and heptakis(6-O-tert-butyldimethylsilyl-2,3-di-O-ethyl)-β-cyclodextrin (TBDE-β-CD) were compared for GC separation of a range of chiral test com-pounds. In particular TXDE-β-CD showed much higher enentio-selectivity than TBDE-β-CD. Enentioselectivities of IPDE-β-CD and CHDE-β-CD are somewhat lower than that of TXDE-β-CD and CHDE-β-Cd are somewhat lower than that of TXDE-β-CD. These observations are indicative of significant effects of subtle changes in the structure of the 6-O-substituent on the enantioselec-tivity of the β-CD derivatives. The difference in enantioselectivities of the 6-O-substituted CD derivatives were explained in terms of relative contributions of the effects of hydrophobicity and steric hindrance of the substituent to the inclusion process. CHDE-β-CD showed the lowest enantioselectivity among the threederivatives. It is likely that the unfavorable steric hindrance of the bulky cyclo-hexyl group plays a greater role than the favorable hydrophobicity effect of the cyclohexyl group in the inclusion process in CHDE-β-CD. IPDE-β-CD showed lower selectivity than TXDE-β-CD and TBDE-β-CD. In the case of these CD derivatives having acyclic substituents the relative hydrophobicity of the substituent seems to be a dominant factor affecting the inclusion process. Isopropyl groups factor affecting the inclusion process. Isopropyl groups are less hydrophobic than thexyl and tert-butyl groups.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/jhrc.1240200808
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    The variation of carrier gas viscosities with temperature (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 471-481 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Carrier gas ; Gas viscosities ; Kinetic theory of gases ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: After describing simplified equations exspressing the temparature dependency of the viscosity of carrier gases (helium, nitrogen and hydrogen ) relative to a base value, absolute relationships based on the kinetic theory of gases are discussed. Comparative data obtained using various calculation methods are given and are compared to measured values. Based on the kinetic relationshipsm, of viscosity. Finally, the influence of pressure on the viscosity is also briefly discussed. As a supplement, Viscosity data are tabulated for the three gases in the range of 0°C to 400°C in increments of 2 K, calculated using the kinetic relationships.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/jhrc.1240200903
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    On-line determination of organophosphorus pesticides in water by solid-phase microextraction and gas chromatography with thermionic-selective detection (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 487-492 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography with thermionic-selective detection ; Solid-phase microextraction ; Organophosphorus pesticides ; Water analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper describes the extraction of 49 organophosphorus pesti-cides (OPPs) from water samples using solid-phase microextraction (SPME). Three fibers, including a 15-μm XAD-coated fiber, a 85-μm polyacrylate-coated fiber, and a 30-μm polydimethylsilox-ane-coated fiber (PDMS), were evaluated here. The effects of stirring and the addition of NaCl to the sample were examined for the polyacrylate-coated fiber. The precision of the technique was examined for all three fibers and the extraction kinetics were investigated using the XAD- and polyacrylate-coated fibers. With some exceptions, the XAD- and polyacrylate-coated fibers performed better than the PDMS-coated fiber. The superiority of the XAD-nd polyacrylate-coated fiber. The superiority of the XAD- and polyacrylate-coated fibers over the PDMS-coated fibers can be attribuibuted to the aromatic functionalities of the XAD and the polar functionalities in the polyacrylate. The relatively high percent RSDs indicate that the SPME technique needs to be further refined before it can be used for anything other than screening. A more effective form of agitation than mechanical stirring may be neccessary to reduce variability and achieve a faster equilibrium between the sample and the SPME fiber.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200905
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    Cyclodextrin derivatives in GC separation of racemic mixtures of volatiles - part XII: Thick-film wide-bore columns for enantiomer GC preparation (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 493-498 
    Details
    ISSN: 0935-6304
    Keywords: Cyclodextrin derivatives ; Enantiomer micropreparative GC ; Thick-film wide-bore columns ; Column loading capacity ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preliminary results on thick-film wide-bore (0.53mm i.d.) columns for GC preparation of pure enantiomers are described. In particular the loading capacity for several racemates of a 3μm, 30% 2,6-di-O-methyl-3-O-Pentyl-β-CD/OV1701 column and of a 2 μm, 30% 2,3-di-O-acetyl-6-O-dimethyl-t-butylyl-β-CD/PS-086 collumn were determined. Consideration is also given to the relation-ship between resolution values of two enantiomers on anayltical columns and their loading capacity and scaling-up to the corresponding micropreparative columns.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200906
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  • 80
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    Electronic Resource
    Quantitation of some flavor components responsible for the “green” attributes in virgin olive oils (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 507-510 
    Details
    ISSN: 0935-6304
    Keywords: Dynamic head space ; Quantitation ; Virgin olive oil ; Lipoxygenase pathway ; Green sensory attributes ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200909
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  • 81
    Electronic Resource
    Electronic Resource
    Supercritical fluid extraction of Peumus boldus (Molina) (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 511-515 
    Details
    ISSN: 0935-6304
    Keywords: Supercritical fluid extraction (SFE) ; Preparative SFE ; High resolution gas chromatography (HRGC) ; Gas chromatography coupled with mass spectromestry (GC/MS) ; Peumus boldus Molina ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200910
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  • 82
    Electronic Resource
    Electronic Resource
    Discover the latest advances in natural product analysis (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 519-519 
    Details
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200912
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  • 83
    Electronic Resource
    Electronic Resource
    Chromatography calendar (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 520-520 
    Details
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200913
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  • 84
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    Enantiomeric separation of 5-alkyl-5methylhydantion derivatives by capillary gas chromatography on permethylated β-cyclodextrin and molecular modeling (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 560-564 
    Details
    ISSN: 0935-6304
    Keywords: Chiral discrimination ; 2,3,6-Tri-O-methyl)-β-cyclodextrin ; Capillary Gas Chromatography ; ?-Alkyl-5-methylhydantoin ; Thermodynamic parameters ; Molecular modeing ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Permethylated β-cyclodextrin (hereafter designated perMe-β-CD), dililuted or not in polysiloxane, is an efficient chiral discriminant for native, 3-methylated, and 1,3-dimethylated series of 5-methyl-5-(CnH2n + 1)hydantoins. From thermodynamic data obtained with pure perMe-β-CD and with the aid of molecular modeling, it is concluded that: (i) For native hydantoin derivatives having a carbon chain at the 5-position varying from ethyl to nonyl (2≤n≤9), the retention time is related to their H-bonding capability. The resolution is poor for derivatives with n≤4. For n≤5, the resolution is considerably improved and this increase in resolution is attributed to the long alkyl chain being capable of being buried inside the cyclodextrin cavity. (ii) For 1,3-dimethylhydantion derivatives having a carbon chain at the 5-position varying from ethyl to hexyl(2≤n≤6), the retention time is mainly determined by a steric fit between the solute and the inner volume of the macrocyclic cavity. For n = 2, a particular behavior is observed, consistent with a total inclusion of the solutes inside the cavity. By contrast with the native hydantoins, the selectively is high for light derivatives. Thus, the selectivity does not correlate with a strong docking energy (such as the presence of H-bonds postulated with native derivatives). (iii) For 3-methylhydantoin derivatives having a carbon chain at the 5-position varying from ethyl to octyl (2≤n≤8), as expected, retension time and selectivity are intermediate between that of native hydantoins and 1,3-dimethylhydantoins. For all three series, where n≤5, the increase in chain length (n) does not bring about substantial changes in the chromatographic results. Therefore, for these long alkyl chain derivatives, similar dominant interactions with perMe-β-CD are postulated.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240201008
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  • 85
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    Chemical characterization of ozonated lignin solutions from corn (Zea mays) stalk and poplar (Populus deltoides) wood by capillary gas chromatography (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 565-568 
    Details
    ISSN: 0935-6304
    Keywords: Capillary GC ; GC-MS ; Corn stalk and poplar wood lignins ; Ozone ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Corn (Zea mays) stalk and poplar (Populus deltoides) wood lignin was converted into monomeric aromatic compounds and short chain aliphatic carboxylic acids. The main reaction products were separated and identified using capillary gas chromatography-mass spectrometry on an HP-5 column. The compounds were considered as positively identified when their mass spectra and GC retention times agreed with those of authentic standard samples. The quantitative estimation of the identified reaction products was accomplished on an OV-101 capillary column by gas chromatography-FID using the internal standard method. Among the aromatic compounds, aldehydes (p-hydroxybenzaldehyde, vanillin, and syringaldehyde), acids (p-hydroxybenzoic, vanillic, 3,4-dihydroxybenzoic, and syringic), and one phenol (hydroquinone) were determined. In addition, the aliphatic carboxylic acids: glycolic, oxalic, malonic, glyoxylic, butanedioic, glyceric, and malic acid were identified. All the calibration curves of the quantified compounds approximated to a straight line. For both corn stalk and poplar wood lignins, the major components were the aromatic aldehydes (71 and 64% of the characterized fraction, respectively), followed by the aliphatic carboxylic acids (20 and 21% of the characterized fraction, respectively).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240201009
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  • 86
    Electronic Resource
    Electronic Resource
    Triglyceride characterization of different mexican cheeses by high temperature capillary gas chromatography (HT-CGC) (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 572-574 
    Details
    ISSN: 0935-6304
    Keywords: high temperature-capillary gas chromatography ; Lipid analysis in cheese ; Milk fat analysis ; Triglycerides in cheese samples ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240201011
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  • 87
    Electronic Resource
    Electronic Resource
    Masthead (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997) 
    Details
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240201101
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  • 88
    Electronic Resource
    Electronic Resource
    Determination of acylglycerols in vegetable oil methyl esters by on-line normal phase LC-GC (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 581-585 
    Details
    ISSN: 0935-6304
    Keywords: On-line LC-GC ; Loop type interface ; Mono-, di-, triacylglycerols ; Vegetable oil methyl esters ; Biodiesel ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An on-line LC-GC method for the analysis of mono-, di-, and triacylglycerols in vegetable oil methyl esters has been developed. The concentrations of these components have turned out to be key parameters for the quality of diesel fuel substitutes. Separation of all classes of acylglycerols from the fatty acid methyl ester matrix is achieved by LC after acetylation of the hydroxyl groups. The acylglycerol fraction is transferred on-line to GC, using the loop-type interface and concurrent eluent evaporation. Quantification of mono-, di-, and triacylglycerols is performed by combining external calibration with internal standardization. Both recovery of the procedure and reproducibility of the quantitative results are evaluated.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240201103
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  • 89
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    Electronic Resource
    Solid phase extraction of organophosphorus, triazine, and triazole-derived pesticides from water samples. A critical study (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 591-596 
    Details
    ISSN: 0935-6304
    Keywords: Pesticide residue analysis ; Solid phase extraction ; Water analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A critical study using C18 SPE columns for the determination of organophosphorus, triazine, and triazole-derived pesticides, nap-ropamide, and amitraz is presented. The type of sorbent, sorbent mass, flow rate in the extraction process, sample concentration of the different compounds, sample volume, pH, and ionic strength were evaluated. Special emphasis was placed on the evaporation step of eluates prior to GC determinations and on prefiltration of sample waters. Pesticide recovery is linear over a wide range of concentrations for most of compounds under study. Under general extraction conditions losses can be expected for amitraz, pro-metryn, prometon, dimethoate, penconazole, and propiconazole. At 100 ng L-1, enhanced responses are produced for mevinphos, simazine, malathion, triadimefon, methidathion, and phosmet, which can be attributed to matrix effects. At basic pH, recovery of prometon, prometryn, and penconazole are improved. Low flow rates and high ionic strength enhance the recovery of prometon and prometryn. For phosmet, the influence of sample volume was established. Likewise, the influence of sorbent quantity was established for phosmet and dimethoate. Losses during the evaporation step were observed for mevinphos, dimethoate (〉 50%), penconazole, propiconazole, and prometon (30%). Prefiltration of sample waters did not cause significant variations in the whole process of extraction. Impurities arising from the sorbent materials were not detected.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240201105
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  • 90
    Electronic Resource
    Electronic Resource
    Comparison of mathemical methods for the calculation of retention indices at high temperature in gas chromatography (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 605-610 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Retention index ; Homologous series ; Local cubic interpolation model ; Multiparametric least-squares adjustsment ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The retention indices of three homologous series (2-alkanones, 1-alkanols, cycloalksanones) have been determined at high temperature by the application of two new adaptation methods: A multiparametric least-squares regressions iterative method based on the dertermination of the adjusted retention times and a cubic interpolation directly using the uncorrected retention times without dead time correction. The two methods were applied to two types of columns. The first group includes eight packed columns (seven OV polymethylphenylsiloxane and Apolane-87 stationary phases), while the second includes five glass capillary columns (four methyl-silicons with different film thicknesses and Apolane-87 stationary phases). The retention indices obtained with a multiparametric and a cubic interpolation methods were compared with each other and with those calculated by Grobler's, Guardino's, Kaiser's and Kovàts' methods. The influence of coating, film thickness, and temperature on them was investigated.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240201107
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  • 91
    Electronic Resource
    Electronic Resource
    Construction of an interface for SPME-PCSFC (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 619-620 
    Details
    ISSN: 0935-6304
    Keywords: Solid Phase micro-extracton (SPME) ; Packed Column supercritical fluid chromatography(PCSFC) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240201110
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  • 92
    Electronic Resource
    Electronic Resource
    Chromatography calendar (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. VII 
    Details
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240201113
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  • 93
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    Electronic Resource
    Stationary phases 44Part 43 of this series, see reference [1].: Chromatographic separation of naturally occurring dehydroiso-α-lapachone derivatives with C60-fullerencel stationary phase (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 624-628 
    Details
    ISSN: 0935-6304
    Keywords: HPLC ; C60-fullerene stationary phase ; Dehydroiso-α-lapachome ; Quinones ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240201112
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  • 94
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    Electronic Resource
    Comparision of varuious bulk fluids and modifiers as near-crtical mobile phases on a polymeric column using linear solvatio energy realationships (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 631-637 
    Details
    ISSN: 0935-6304
    Keywords: High Perfromance liquid chromatography ; supercritical fluid chromatography ; Selectivity ; Hydrogen bonding ; Linear solvation energy relationships ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Linear solvation energy realationships (LSERS) were used to qunatitatively compare the relative contributions of dipolarity/polarizability, hydrogen bonding, and other types of intermolecular interactions to retention and selectivity using various bulk moblie phase component. Using experimental condition which differ only by the compostion of the bulk moble phase component, the factors which cause selctivity to differ between HPLC, subcritical fluid chromatography and supercritical fluid charomatography were decovoluted. Heptance-based HPLC mobile phases showed superior selectivities towards analytes which differ in hydrogen bond donating ability, gas-to-hexadecane partion coefficint and dipolarity/ploarizability. subcritical fluid chromatography with HFC-134a (1, 1, 1, 2-tetrafluoroethane) as the bulk fluid produced superior seclectivities for which differ in hydrogen bond accepting ability and execess molar refraction properties. Many of these factors showed temperature dependences which act to attenuate or accenture the particular intermolcular interaction.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240201203
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  • 95
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    Electronic Resource
    Tris (2,2′-bipyridyl)ruthenium (III) as a chemiluminescent reagent for detection in capillary electrophresis (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 643-646 
    Details
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis ; Electogenerated chemiluminescence ; Ru(bpy)32+ ; Tripropylamine ; Proline ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A post- column chemiluminescent technique for thedetection of compounds that are poor chromoshores using electorogenerated chemiluminescence following separation by capillartgy electrophoresis is described. The luminrescent signal is generated followintg the reaction of anlyres (e.g. amines) with Ru(bpy)33+, which isx electrochemically generated post-columan from Ru(bpy)32+. Tripropylamine and proline are used as two model compounds to demostrate the feasibility of the method. Detection limits for the prototype system were in the micromolar rage, suggesting that this technnique offers an alternative to indirect detection of compounds that are poor chromophores with an added selectivity advangage. The system includes the use of a conductive joint to isolate the separation field from the potential necessary to drive the elctrogenerated chemiluminescent reactiion. Addition of the chemiluminescent reagent Ru(bpy)32+ post-column did not decrease the efficiency of the separation. The design and favrication of the novel cell is discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240201205
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  • 96
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    Electronic Resource
    Separation of metal cations in acidic solution by capillary electrophoresis with direct and indirect UV detection (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 653-656 
    Details
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis ; Metal cations ; Acid solution ; UV detection, direct and indirect ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methods for the detectionn of metal cations under acidic conditions, near PH 2, in capillary electrophoresis (CE) were investigatged. Conditions for direct UV detection of UV absorbing metal cations such as Cr3+, Cu2+, Fe3+, UO22+, VO2+, and VO2+ were established With aqueous HCl or HClO4 as the electroyte carrier. The speciation of vanadium(IV) and vanadium(V) at PH 2.3 by CE was achieved with direct detection at 185 nm. With the strong absorbance at 185 nm, no complexation was needed to detect the metal cations. An indirect UV detrection scheme for acidic conditions was also investigated. Several background carrier electolytes (BCES) were studied including 4-methylbenzylamince, nicontinamide, pyridazine, guanidine, 3-picoline, and chromium (III) to determine their effectivencess under very acidic conditions. The efect of ioni c surfactants and the nonionic surfactant, Trition X-100, on the peak heights and N Values was also studied.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240201207
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  • 97
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    Electronic Resource
    Determination of solvent recondensation or evaporation in the GC-precolumn by measurement of temperature changes on the column wall (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 657-664 
    Details
    ISSN: 0935-6304
    Keywords: Temperature measurement on column wall ; Solvent recondensation in the precolumn ; Closure of Vapor exit ; Vaporizer/precolumn solvent split ; Loop-type interface ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Temperature measurements on the column outer well were used for detecting recondensation or evaporation of solvent inside the precolumn during injection or on-line transfer of large solvent volumes. This facilitates the choice of the most critical parameter of these techniques, i.e. oven temperature. When using the vaporizer/precolumn solvent split/gas discharge system, the dew point of the solvent is determined, either to just prevent solvent recondensation or to limit it to the capacity of the precolumn to retain liquid. In concurrent eluent evaporation through the loop type LC-GC interface, temperature measurement enables the determination of whether or not the flooded zone exceeds a given limit. Fanally, when solvent trapping is used (on-column injector/partially concurrent solvent evaporation evaporation or vaporizer/partial recondensation), temperature measurement near the front end of the flooded zone is used as a signal for accurate closure of the vapor exit shortly before the end of solvent evaporation.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240201208
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  • 98
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    Electronic Resource
    Theory of fast capillary gas chromatography part. 2: Speed of analysis (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 679-687 
    Details
    ISSN: 0935-6304
    Keywords: Efficiency-optimized column ; Efficiency-optimized gas velocity ; Fast GC ; High pressure drop ; Speed of analysis ; Speed-optimized column ; Speed-optimized gas velocity ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using hold-up time as a measure of the speed of analysis with a given column efficiency, a theory of pneumatic optimization of a column in the fast high pressure drop isothermal and temperature programmed GC is developed. Expression for the hold-up time as a function of column efficiency, carrier gas velocity and film thickness is derived. Also found are the expressions for the minimum hold-up time and optimum gas velocity in a speed-optimized column. These quantities are compared with their counterparts in the efficiency-optimized column.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240201212
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  • 99
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    Electronic Resource
    A reversed phase high-performance liquid chromatography method for determination of cephalexin in human plasma (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 674-678 
    Details
    ISSN: 0935-6304
    Keywords: HPLC ; LC-MS/MS ; Validation ; Cephalexin ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A reversed-phase HPLC method for the analysis of cephalexin (7-[(aminophenylacetyl)amino]-3-methyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid) by isocratic separation is described. A comparison is made between the ultrafiltration land the extraction procedure developed in our laboratory. The extraction procedure, based on the deproteinization of plasma with perchloric acid followed by the extraction with dichloroethane and separation of cephalexin on a reversed phase column, gave better recovery. Quantitative validation of our method has been performed by an external standard technique. The relative standard deviations were between 1.1 and 1.9% in the within-day assay and between 1.2 and 2.2% in the inter-day assay. The limit of detection was 0.14ug/ml and the limit of quantification was 0.28ug/ml. This method is rapid, sensitive, simple, and reproducible. The LC MS/MS technique was successfully used for identification and quantification of cephalexin in human plasma samples.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240201211
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  • 100
    Electronic Resource
    Electronic Resource
    Troubleshooting in the separation sciences (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 703-703 
    Details
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240201217
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