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  • ZIB Catalog
  • Articles: DFG German National Licenses  (1,600)
  • 1990-1994  (1,600)
  • 1993  (1,600)
  • Analytical Chemistry and Spectroscopy  (1,600)
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  • ZIB Catalog
  • Articles: DFG German National Licenses  (1,600)
Material
Years
  • 1990-1994  (1,600)
Year
  • 1
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Analytical methods have been developed for the simultaneous quantitation of azelastine (AZ) and desmethylazelastine (DAZ) in guinea pig plasma and lung tissue. The methods require a 1.00 mL plasma sample and a minimum 0.100 g lung sample. Both methods employ liquid/liquid organic extraction and back-extraction into dilute acid. Quantitation is performed by high performance liquid chromatography on a 2X250 mm 5 μm HypersilTM CPS column using fluroescence detection. The linear quantitative ranges for AZ.HCI and DAZ.HBr in plasma are 0.156-160 ng/mL and 0.313-160 ng/mL, respectively. The linear quantitative ranges for AZ.HCI and DAZ.HBr in lung tissue are 0.039-20 μg/g for both.
    Additional Material: 2 Ill.
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  • 2
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A rapid, sensitive and simple to operate high performance liquid chromatographic method for the simultaneous determination of morphine, morphine-3-glucuronide and morphine-6-glucuronide in plasma is described. The drug and its metabolites were extracted from plasma using commercially available reversed phase octylsilane bonded silica columns (1 mL Bond Elut C8, 50 mg). Chromatographic separation of morphine and its metabolites was achieved using a mobile phase, consisting of 2 mM sodium dodecyl sulphate in 0.05% phosphoric acid:acetonitrile (71.5:28.5 by volume), at a flow-rate of 1.2 mL/min, in conjunction with a Waters Nova-Pak C18 column (300 × 3.9 mm). The analytical column was used in combination with a Guard-Pak module containing a Nova-Pak C18 Guard-Pak insert. Using fluorescence detection (excitation 245 nm, emission 335 nm), plasma levels in the region of 5-10 μg/L for the drug and its metabolites can be detected with only 200 μL of plasma. The method has been applied to studies of the disposition of morphine and its metabolites in premature neonates requiring mechanical ventilation who were receiving the drug intravenously; preliminary findings in patients at steady state are presented.
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  • 3
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A multidimensional column chromatographic method involving electrochemical detection using a carbon fibre microelectrode flow cell was optimized and successfully applied to the simultaneous determination of salbutamol and terbutaline in plasma at overdose levels. This method performs, in a single step, an efficient extraction and clean-up of salbutamol and terbutaline from human plasma. The calibration graphs over three days were linear over the calibration range 20-100 ng/mL plasma with a limit of detection of 1 ng and 0.8 ng/mL plasma for salbutamol and terbutaline, respectively. The intra- and inter-assay coefficients of variation were less than 8% and the recoveries ranged from 94 to 96%. The accuracy of the assay, which was defined as the percentage difference between the mean concentration found and the theoretical concentration, was 7% or better. The proposed method combines the advantages of being simple, reproducible and selective in the presence of other sympathomimetic and commonly ingested drugs and is suitable for routine analyses to obtain valuable information about the clinical effects and treatment of overdose with these drugs. The whole procedure takes ca. 10 min and compares favorably with detection at a conventional glassy carbon electrode.
    Additional Material: 7 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Biomedical Chromatography 7 (1993), S. 181-183 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A high performance liquid chromatographic method has been developed for the determination of rafoxanide and closantel in ovine plasma. Acetonitrile and chloroform were used for the extraction. The mean recoveries were 78.69% and 80.59% for rafoxanide and closantel, respectively. This method was applied to the characterization of rafoxanide plasma kinetics following oral administration of therapeutic doses to sheep.
    Additional Material: 2 Ill.
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  • 5
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The separation of reduced and oxidized glutathione at an absolute sensitivity of about 100 pg by micellar electrokinetic capillary chromatography without derivatization is described. The time required for the separation is less than 10 min (the time between two following injections is about 15 min). The separation is characterized by high efficiency and good reliability. A partition mechanism is responsible for the high resolution observed. The method was utilized for the analysis of commercial preparations of glutathione and a good agreement with the expected results was obtained; the oxidation of the commercial glutathione in solution was easily analysed.
    Additional Material: 8 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Biomedical Chromatography 7 (1993), S. 235-250 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Application of HPLC as a prime tool in the area of enantiomeric resolution has opened doors of success and varied interest. Use of chiral reagents either indirectly (as derivatization reagent) or directly (added to stationary or mobile phase) has led to achieve resolution of a wide range of compounds. Amino acids, being important molecules with simple structure and easy availability, have been extensively studied. A bibliographic survey on HPLC resolution of amino acids and derivatives along with a brief discussion on general methods of enantiomeric separation has been presented.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Biomedical Chromatography 7 (1993), S. ii 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Biomedical Chromatography 7 (1993), S. 275-276 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: L- and D-Amino acids (Leu or Phe) were derivatized with fluorogenic reagents, 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F), 4-(N,N-dimethylaminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole (DBD-F), 4-aminosulfonyl-7-fluoro-2,1,3-benzoxadiazole (ABD-F) and 5-(N,N-dimethylamino)naphthalene-1-sulfonylchloride (DNS-Cl), and separated on a Pirkle type column, Sumichiral OA 2500 (S) ((S)-1-naphthylglycyl-3,5-dinitrophenylamide silica gel) with a mobile phase of 20 mM ammonium acetate in methanol. The fluorometric detection of the derivatives was made at 530 nm, 590 nm and 530 nm with excitation at 470 nm, 450 nm, 450 nm and 350 nm, respectively. The former three derivatives of the enantiomers were separated well from each other; The as for each NBD-, DBD- and ABD-derivative of L- and D-Leu were 1.10, 1.11 and 1.10, respectively. However, the DNS derivatives of L-and D-Leu were not separated (separation factor, α = 1.0). All NBD- and ABD-derivatives of L- and D-Phe were also well separated (αs were 1.18, 1.17 and 1.16, respectively), while DNS-L- and -D-Phe were barely separated (α = 1.04). These data suggest that the 2,1,3-benzoxadiazole (benzofurazan) moiety is very effective and preferable to the dimethylaminonaphthalene sulfonyl (DNS) structure for the separation of enantiomers of amino acids derivatized with benzofurazan reagents.No recemization of each enantiomer occurred during the derivatization reaction with NBD-F, DBD-F and ABD-F at pH 8.0 and 60°C for 2 min, at pH 9.3 and 60°C for 30 min and pH 9.3 and 60°C for 60 min, respectively, meaning that all benzofurazan type fluorogenic reagents are useful for sensitive determination of amino acid enantiomers.
    Additional Material: 1 Ill.
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  • 9
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: This report details a very sensitive, rapid and accurate ion-pair HPLC-ECD method for the analysis of biogenic amines and their metabolites in brain tissue. The method described enables detection of picogram amounts of 3-methoxy-4-hydroxy phenethyleneglycol (MHPG) (37 pg), 3,4-dihydroxy phenylacetic acid (DOPAC) (18 pg), norepinephrine (NE) (12 pg), epinephrine (E) (6 pg), 5-hydroxyindoleacetic acid (5-HIAA) (18 pg), 3,4-dihydroxyphenylethylamine (DA) (6 pg), 3-methoxy-4-hydroxyphenylacetic acid (HVA) (12 pg) and 5-hydroxytryptamine (5-HT) (12 pg). The linearity of the method is from 18.75 ng/mL to 300 ng/mL for MHPG; 9.37 to 150 ng/mL for DOPAC and 5-HIAA; 6.25 to 100 ng/mL for NE, HVA and 5-HT; and from 3.12 to 100 ng/mL for E and DA. The reproducibility, expressed as coefficient of variance (CV%) within-run and between-run groups, was 2.25% and 19.49% for MHPG; 3.84% and 29.84% for DOPAC; 0.89% and 8.97% for NE; 1.26% and 5.61% for E; 1.07% and 28.77% for 5-HIAA; 2.65% and 10.65% for DA; 5.97% and 24.38% for HVA; and 4.44% and 9.45% for 5-HT.
    Additional Material: 1 Ill.
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  • 10
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A procedure for the extraction and high performance liquid chromatographic (HPLC) determination of the photodynamic therapeutic agent 5,10,15,20-tetra(m-hydroxyphenyl)chlorin in human, rat and mouse tissues following intravenous administration of the drug is described. The tissue (tumour, skin, muscle and liver) was homogenized and extracted into a mixture of methanol:dimethyl sulphoxide:water (32:8:1 by vol.) containing, 5,10,15,20-tetra(p-hydroxyphenyl)chlorin as the internal standard. The precipitated proteins were removed by centrifugation and the supernatant was separated by reversed phase HPLC on a Hypersil-ODS column with 77% (v/v) acetonitrile in 0.1% trifluoroacetic acid as the mobile phase. The solute was detected with high sensitivity and specificity by a UV-VIS detector set at 423 nm.
    Additional Material: 2 Ill.
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  • 11
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Biomedical Chromatography 7 (1993), S. 179-179 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 12
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Some L- and D-amino acids (Phe or Leu) were derivatized with a fluorogenic reagent, 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) and separated on a Pirkle-type column, Sumichiral OA 2500(S) [(S)-1-naphthylglycyl-3,5-dinitrophenylamide silica gel] with a mobile phase of 20 mM ammonium acetate in methanol. The fluorometric detection was made at 530 nm with excitation at 470 nm. No racemization of the enantiomers occurred during the derivatization reaction. The separation factors (α) for NBD-L-Phe and NBD-D-Phe, and NBD-L-Leu and NBD-D-Leu, were 1.27 and 1.17, respectively. The detection limits were in the range of ca. 30 fmol.
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  • 13
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Biomedical Chromatography 7 (1993) 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 14
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Biomedical Chromatography 7 (1993), S. 189-195 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A reversed phase high performance liquid chromatographic technique is presented allowing purine catabolite determination in a whole blood extract without a prior purification step. The method was applied to determine the timing and the profile of myocardial nucleotide catabolite release during reperfusion of the transplanted human heart. Samples of arterial and coronary sinus blood collected at various times within 1 h after aortic declamping during heart or heart-lung transplantations were used for nucleotide catabolite determination. Massive release of inosine and hypoxanthine from the heart was demonstrated. Production of adenosine was also shown but there was no liberation of xanthine or uric acid. Nucleotide catabolite release was greatest in the first 5 min (coronary sinus-arterial difference = 15-20 μM), but was still significant after 30 min of reperfusion. The determination of inosine and hypoxanthine--major catabolites released--was found to be reproducible in coronary sinus blood (coefficient of variation 〈 10%). However, immediate protein precipitation afer blood sample collection was necessary, as rapid metabolism of both exogenous and endogenous adenosine and inosine was demonstrated.
    Additional Material: 4 Ill.
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  • 15
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A high performance liquid chromatographic method with chemiluminescence detection for the determination of penicillin G and ampicillin is reported. The method is based on the enhancement of the luminol chemiluminescence with β-lactam antibiotics. The linear relationship was obtained between the peak height and the concentration of penicillin G or ampicillin up to 15 nmol per 20 μL injection. Detection limits were 1 nmol for penicillin G and 0.5 nmol for ampicillin with a signal-to-noise ratio of 2. Relative standard deviations for five replicate measurements of 4 nmol/injection each of penicillin G and ampicillin were 2.1 and 2.3%, respectively.
    Additional Material: 6 Ill.
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  • 16
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Biomedical Chromatography 7 (1993), S. 231-232 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 17
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Biomedical Chromatography 7 (1993) 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 18
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Biomedical Chromatography 7 (1993), S. 48-55 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: We have investigated the hydrophobic properties of human skin fibroblast proteoglycans and related material by affinity chromatography on Octyl-Sepharose CL-4B in 4 M guanidinium hydrochloride (GdnHCI). Proteoglycans and related material could be separated into non-, medium and highly hydrophobic forms by elution with gradients of Triton X-100 in 4 M Gdn HCI. The non-hydrophobic material included endogenously produced glycosaminoglycan chains and oligosaccharides as well as an HS-proteoglycan with a 35 kDa core. The 65-70 kDa core (glypican-related) proteoglycans appeared among the highly hydrophobic ones, but variable proportions were seen both in the medium and the non-hydrophobic material. Other membrane-bound proteoglycans, like fibroglycan (45 kDa core) and the HS-proteoglycans with 90 and 130 kDa cores, as well as the CS/DS-proteoglycan with a 90 kDa core, were all of high hydrophobicity. There were also indications of a highly hydrophobic CS/DS-proteoglycan with a 45 kDa core. The extracellular proteoglycans, PG-L, PG-S1 and PG-S2, and the HS-proteoglycans with 350 and 250 kDa cores were all of medium hydrophobicity. These proteoglycans emerged in distinct positions when the column was eluted with a gradient of 3-[(3-cholamidopropyl)dimethylammonio]propanesulphonate.
    Additional Material: 6 Ill.
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  • 19
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The reactivities between saccharides and primary amino compounds were studied by liquid chromatography on an amino-bonded column and by measurement of the reaction rates of aromatic amines with saccharides. The recoveries from the column and the reaction rates were correlated with their physicochemical properties calculated by the CACheTM program. The reactivities between amines and saccharides correlated well with their hydrogen bonding energies calculated by molecular mechanics.
    Additional Material: 2 Ill.
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  • 20
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Biomedical Chromatography 7 (1993), S. 86-89 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A rapid, sensitive and selective method for the assay of glutathione in cultured cells has been developed using ion-pair reversed phase rapid high performance liquid chromatography. The use of a 4 μm particle, 5 cm long column (Superspher 100 RP 18 end-capped) allowed complete analysis of glutathione within 3 min. A postcolumn derivatization reaction with o-phthaladehyde and fluorometric detection made the assay fully selective with regard to other endogenous thiols and sensitive (the detection limit was 0.5 ng of glutathione injected). The linearity range was between 0.1 and 2.0 μg/mL with good repeatability (relative standard deviation less than 5% for the lowest concentration quantitated). Recoveries of GSH from cultured cell samples were above 98%. The rapid analysis enabled the processing of a large number of samples in a short time (up to 20 per hour). The method was applied to the measurement of the intracellular glutathione amount in V79 fibroblasts along cell growth in culture.
    Additional Material: 3 Ill.
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  • 21
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A stereoselective and sensitive method for the determination of the enantiomers of felodipine, a dihydropyridine calcium antagonist, has been developed and the pharmacokinetic profiles of the enantiomers comparatively studied after oral administration to dogs and humans. D6-Felodipine, the internal standard, was added to the plasma, extracted with a solvent and then optically resolved into S(-) and R(+) enantiomers on a high performance liquid chromatographic Chiralcel OJ column. Each enantiomer in the effluent was analysed by capillary column gas chromatography/positive ion electron impact mass spectrometry. After oral administration of the felodipine racemate, the Tmax and t1/2 values hardly differed between the two enantiomers in dogs and humans. The Cmax and AUC0-24h values of the S(-) enantiomer were slightly higher than those of the R(+) enantiomer in humans but the difference between the enantiomers was not significant. These results suggested that there is no large difference in the absorption, distribution and elimination of felodipine enantiomers after oral administration of the racemate in either dog or human.
    Additional Material: 4 Ill.
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  • 22
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The development of column packing materials was tried as a contribution to studies related to the further modification of 3-aminopropyl-modified silica gel. Consequently, we prepared two types of gel, 3-(1-naphthoylamino)- and 3-(1-anthroylamino)-propyl-modified silica gels (NAPS and AAPS). Since NAPS and AAPS, each having an aromatic ring, were expected to behave in a separation mode by a π-π or hydrophobic interaction, their application to the analyses of the compounds related to nucleic acids was carried out. Adenosine nucleotides were consequently separated by the gels in a single analysis by a single buffer elution with UV detection. NAPS could be also successfully used for the measurement of ATPase activity in fish meat (Sillago japonica). The mobile phase consistently used in the analysis was an aqueous phosphate buffer.
    Additional Material: 4 Ill.
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  • 23
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A selective and sensitive method has been developed for the determination of secondary amines by gas chromatography (GC). After removal of primary amines by the reaction with o-phthaldialdehyde, secondary amines were converted into their N-diethylthiophosphoryl derivatives and then measured by GC with flame photometric detection using a DB-1701 capillary column. The derivatives were sufficiently volatile and stable to give single symmetrical peaks. The detection limits of secondary amines were ca. 0.05-0.2 pmol per injection. N-Methylcyclohexylamine was used as an internal standard. The calibration curves for secondary amines in the range 1-20 nmol were linear and sufficiently reproducible for quantitative determination. This method was successfully applied to small urine samples without prior clean-up. Overall recoveries of secondary amines added to urine samples were 91-105%. By using this method, secondary amines in urine samples could be analysed without any influence from primary amines and other coexisting substances. The analytical results of secondary amine content in urine samples of normal subjects are presented.
    Additional Material: 4 Ill.
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  • 24
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A method has been developed for the quantitative analysis of clomipramine and its major metabolite desmethylclomipramine in plasma, using normal phase chromatography with UV detection at 254 nm. This rapid (6 min) and highly sensitive methodology (detection limits 0.5 ng/mL and 2 ng/mL for clomipramine and desmethylclomipramine, respectively; S/N = 3, 0.001 aufs) allows pharmacokinetic studies and drug monitoring of the two compounds. Using the described methodology we report an application which involved 10 depressed inpatients.
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  • 25
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A simple, selective, reversed phase liquid chromatographic method using a column-switching technique has been developed for the simultaneous determination of a novel derivative of etoposide (NK611) and its O-demethyl metabolite in dog plasma. A good linear response was obtained for both drugs in the range 0.1-12.0 μg/mL. The mean recoveries were within 100±5%. The within- and between-day precisions were within 3.5% and 4.6%, respectively. This method was used in a pharmacokinetic study following intravenous and oral administration of NK611 to beagle dogs.
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  • 26
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Biomedical Chromatography 7 (1993), S. 94-98 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Two forms of liver metallothioneins (MTs) were purified from hedgehog exposed to zinc, using gel filtration on Sephacryl S-100 and DEAE Sepharose Fast Flow chromatography. The peptide chain weight of both MT-1 and MT-2 was found to be about 10,000, as determined by high performance liquid chromatography. This value was higher than that calculated from amino acid analysis. The amino acid composition of hedgehog liver MT-1 and MT-2 resembles that of liver to MTs from rabbit and other species. Their distinctive features include an extremely high cysteine content, about 33% of all the amino acid residues, and an absence of aromatic amino acids and histidine. In addition, a rapid method for the determination of MTs during animal tissue purification has been established. The samples were directly added in an ammoniacal solution of a Co(II) salt for recording linear sweep polarograms. By comparison with the commonly used metal determination method, our method is direct, rapid, credible and suitable for all the MTs or MT-like samples.
    Additional Material: 6 Ill.
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  • 27
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A reversed phase high performance liquid chromatographic method for the high sensitivity determination of individual bile acids in serum using a C18 column with a ternary solvent system combined with fluorometric techniques using immobilized enzymes is described. A computer-assisted diagnosis system using pattern recognition was developed to assist the clinical diagnosis of various liver and biliary diseases. A total consistency rate of 95% can be reached using this system.
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  • 28
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Biomedical Chromatography 7 (1993), S. 143-145 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Human pancreatic carboxypeptidase A, which was isolated from a pool of necrobiotic pancreae, crystallized spontaneously and appeared homogeneous in sodium dodecylsulphate polyacrylamide gel electrophoresis. Reversed phase high performance liquid chromatography of the dissolved crystals, however, revealed the presence of two distinct isoenzymes, which were shown by aminoterminal sequence analysis to be only 61% homologeous in their 31 amino terminal amino acids. On the other hand, amino terminal sequences of the isoenzymes were found to be 79% and 87% homologeous with CAP 1 and CPA 2 of the rat, respectively. Thus, the presence of two distinct pancreatic carboxypeptidase A isoenzymes could be clearly demonstrated for the first time in human tissue.
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  • 29
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Biomedical Chromatography 7 (1993), S. 200-203 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Formation of free radicals and lipoperoxidation occur at the onset of cellular damage. These effects are produced during normal metabolism and in pathological states. The peroxidation of polyunsaturated fatty acids, i.e. linoleic acid and linolenic acid, which are both cellular membrane compounds, induces ethane and pentane formation in pulmonary air exhalation. These two volatile hydrocarbons can be considered as potential lipoperoxidation markers. Methodological difficulties limit the use of these gases for assessment of free oxygen radical activity but we have developed and validated a non-invasive technique. A study was performed with ten healthy volunteers.
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  • 30
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A gas chromatographic method for the determination of mexiletine in human plasma is described. Mexiletine was simultaneously extracted and derivatized with carbon disulphide for separation and quantitation on a glass column (1.5 m × 3 mm i.d.) packed with 1.5% OV-1 coated on 80-100 mesh Shimalite W (201D). The method required only 0.5 mL of plasma and could detect as little as 10 ng of mexiletine. It has been applied to the study of the pharmacokinetics of mexiletine in healthy volunteers.
    Additional Material: 5 Ill.
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  • 31
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Fluorescence and chemiluminescence analyses of amino acids and thiols derivatized with 2-fluoro-4,5-diphenyloxazole (DIFOX) and 2-chloro-4,5-bis(p-N,N-dimethylaminosulphonylphenyl)oxazole (SAOX-CI) were investigated. Thirteen diphenyloxazole (DIOX)-derivatized amino acids were separated within 38 min by a linear gradient elution from 100% A [0.05 M phosphate (pH 7.0):CH3CN (75:25)] to 100% B [0.05 M phosphate (pH 7.0):CH3CN (1:1)] over 30 min and an isocratic elution of 100% B for 30 min. The detection limits (S/N = 2) with fluorescence detection were in the range of 19-64 fmol. Thiols derivatized with SAOX-CI were separated by an isocratic elution using 0.1 M H3PO4:CH3CN (65:35) and detected fluorimetrically. The detection limits (S/N = 2) of reduced glutathione, N-acetylcysteine, 2-mercaptopropionylglycine, cysteine, homocysteine and captopril were 1.2, 1.5, 1.9, 5.7, 6.4 and 7.9 fmol, respectively. Peroxyoxalate chemiluminescence (CL) intensities of sulphonyl-5-N,N-dimethylaminonaphthalene (DNS), SAOX and DIOX derivatives were compared using three different oxalate esters (DFPO, TCPO and TDPO) by flow injection analysis. The relative chemiluminescence intensity (RCL) of SAOX-proline and DIOX-proline were 76-80% and 19-25% of DNS-proline (100%), respectively. Other SAOX and DIOX derivatives showed lower CL intensities ( 〈 12%). Extremely low CL intensities were obtained for the fluorescent tagging reagents (〈0.11%) and their hydrolysis products (〈0.80%). Secondary amino acids and peptides, derivatized with DIFOX in aqueous media at room temperature for 1 h, were detected using DFPO/H2O2. TCPO/H2O2 and TDPO/H2O2 after separation by high performance liquid chromatography. The detection limits (S/N = 2) of hydroxy-L-proline, L-proline, L-prolyl-glycyl-glycine and L-prolyl-L-leucine with the three oxalate esters were 10-17 fmol, 22-34 fmol, 50-61 fmol and 80-123 fmol, respectively.
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  • 32
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Biomedical Chromatography 7 (1993), S. ii 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 33
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    Biomedical Chromatography 7 (1993), S. 229-230 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A sensitive and selective reversed phase high performance liquid chromatographic method was introduced for the determination of salmon calcitonin (sCT) in solutions containing bovine serum albumin or gelatin. The method was based on the sensitive fluorescence detection of sCT by postcolumn derivatization with o-phthal(di)aldehyde. The sample was loaded onto a reversed phase column, purified by column switching and separated with linear gradient elution using the ion pair technique. A linear relationship was obtained between the peak height and the amount injected in the concentration range 1-40 ng. The detection limit was 10 ng/mL (S/N = 3) at a sample injection volume of 100 μL.
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  • 34
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    Biomedical Chromatography 7 (1993), S. 256-261 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Amyloglucosidase from Halobacterium sodomense was purified by a combination of hydrophobic interaction chromatography and immobilized metal ion affinity chromatography at analytical and preparative scale with 75% recovery. The enzyme was found to be a dimer of two different subunits with molecular weights of 72,000 and 82,000 D, respectively, combining in a 175,000 D native protein. The specific activity, KM, and amino acid composition of the enzyme was determined.
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  • 35
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    Biomedical Chromatography 7 (1993), S. 273-274 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A sensitive (up to nanogram level) method for resolving a cannabinoid mixture in plasma is described. Cannabinoids were extracted with a C-18 Sep Pak cartridge and derivatized with dansylchloride. Then the derivatives were resolved on thin layer HPTLC silica plates which were developed and quantified by fluorescence densitometry at 340 nm.
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  • 36
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The recent developments in enantioselective HPLC-separation techniques are impressive and are driven by industrial and academic interests; thus there is for instance a high demand for developing stereoselective assays for chiral drugs in biological fluids. The beta-blocking agents, which possess an amino- propanol- or -ethanol side chain with at least one chiral centre, represent one of the most intensively investigated groups of more than 40 drugs introduced world wide. Seven of the most popular beta-blockers were chosen as representatives: atenolol; betaxolol; carvedilol; metoprolol; pindolol; propranolol; and sotalol, these span the whole range of lipophilicity to hydrophilicity (polarity). Enantioselective HPLC bioassays for these β-blockers published so far, including techniques based on chiral derivatizing agents (CDAs), chiral stationary phases (CSPs) and chiral mobile phase additives (CMPAs) have been reviewed and documented in the light of general aspects together with pharmacokinetic and pharmacodynamic considerations.
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  • 37
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    New York, NY : Wiley-Blackwell
    Biomedical Chromatography 7 (1993), S. ii 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 38
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    Biomedical Chromatography 7 (1993), S. 227-228 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A high performance liquid chromatographic (HPLC) method has been developed for the determination of levomepromazine in human breast milk and serum. The levomepromazine was extracted by a rapid and simple extraction method using a Sep-Pak C18 cartridge. The extracts were separated by HPLC on a C8 bonded reversed phase column and detected by UV absorbance at 254 nm. There was no interference with endogenous substance in human breast milk and serum. A linear relationship was obtained for the levomepromazine over the concentration range of 10-300 ng/mL. The recoveries of levomepromazine added to human breast milk and serum were 92.5-99.1% and 86.9-103.9%, respectively.
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  • 39
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    Biomedical Chromatography 7 (1993), S. 233-233 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 40
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A sensitive HPLC method has been described for quantitation of two cholecystokinin (CCK) peptides in discrete rat brain regions. Separation and quantitation was performed by the reversed-phase HPLC combined with electrochemical detection. Analytical recoveries of the tetrapeptide (CCK-4) and octapeptide-sulphate (CCK-8s) were 96% and 94%, respectively. The between assay coefficient of variation (CV) was less than 3% for both peptides. The within-assay CV was 4% and 6% for CCK-4 and CCK-8s and the detection limit was 2 and 10 pmol/mL, respectively.For identification of structures, the peptides were fractionated by semi-preparative HPLC using a novel SMART system for micropurification. The fractions were analysed by fast atom bombardment mass spectrometry (FAB MS) which confirmed the presence of both CCK-4 and CCK-8s in the rat brain tissue.
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  • 41
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    Biomedical Chromatography 7 (1993), S. 267-272 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Reliable measurement of the reduced and oxidized forms of ascorbic acid (AA) is challenging because they are highly reactive and unstable compounds. Detection of small amounts of AA and dehydroascorbic acid (DHAA) is essential for determining the biochemical function of the vitamin. While a variety of techniques exist for measurement of AA with detection limits in the millimolar range, a need exists for highly reliable assessment of picomolar levels of AA and DHAA in tissues. The present study presents a method for measuring AA and DHAA that combines high performance liquid chromatography with the advantages and increased detection limits and selectivity available with coulometric electrochemical detection. The difference between AA and „total AA“ in tissue samples gives an assessment of DHAA concentration. Verification of the reliability of assay is by the successful linear recovery of exogenously added AA and DHAA in tissue homogenate. Optimal conditions for reducing DHAA in tissue samples include a pH of 7.2, reaction time of 10 min, reaction temperature equal to room temperature, and a 10 mM concentration of the reducing agent, β-mercaptoethanol. AA and DHAA are measured in several mammalian tissues using the method presented.
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  • 42
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    New York, NY : Wiley-Blackwell
    Biomedical Chromatography 7 (1993) 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 43
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    Biomedical Chromatography 7 (1993), S. 12-14 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The diuretic drug hydrochlorothiazide (HCT) is used mainly for treatment of mild to moderate hypertension and is usually administered with other drugs. An assay for the determination of HCT in human plasma and urine by high performance liquid chromatography (HPLC) has been developed. Samples were purified by solvent extraction and analysed by reversed phase HPLC with ultraviolet detection, using hydroflumethiazide as the internal standard; plasma was eluted using gradient elution and urine was analysed isocratically. The method is simple to perform, is sensitive (detection limit 0.01 μg/mL in plasma and 0.2 μg/mL for urine); it showed good reproducibility (3-8%). A great number of drugs did not interfere with the assay and the method was used for pharmacokinetic studies in healthy subjects, but samples from patients can also be analysed with high selectivity.
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  • 44
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Hydrophilic peptides generated from enzymic fragmentation of proteins are difficult to purify because they are either weakly bound or unretained by the reversed phase C18 columns favoured for liquid chromatographic separation of peptide mixtures. To overcome this difficulty, peptides that were not bound or only weakly bound by a C18 RP column were reacted with phenyl isothiocyanate (PITC), as used in the initial step in Edman sequencing. The hydrophobic phenylthiocarbamyl (PTC) peptide derivatives produced by the reaction were rechromatographed on the same column. Peptides generated by tryptic digestion of equine cytochrome C were used as a model system to test whether a complete set of peptide fragments could be purified by this method using just one column and solvent system. All the expected hydrophobic tryptic peptides bound to the RP column and were resolved by elution with acetonitrile, but no hydrophilic peptides were recovered as pure fractions. The column breakthrough fraction was reacted with PITC and rechromatographed on the same column, producing a profile consisting of 19 bound peaks. Further rechromatography of some of the fractions at different column temperatures enabled all six of the expected hydrophilic peptides to be purified and identified. The technique has also been applied to the sequence determination of coat protein from peanut stripe potyvirus protein, eight hydrophilic tryptic peptides being recovered and identified as PTC derivatives.
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  • 45
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    Biomedical Chromatography 7 (1993), S. 20-24 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Propoxur (Baygon, 2-isopropoxyphenyl N-methylcarbamate) is a carbamate pesticide commonly used against house insects. When the insecticide was administered intramuscularly in rats it was converted to a new metabolite which was found to be present in the serum, liver, kidney and brain 6 h after the administration of the pesticide. The metabolite was purified by high performance liquid to chromatography and comparison of the infrared spectra of Propoxur and the metabolite showed that a deamination reaction was responsible for the formation of the metabolite from the parent pesticide. The pesticide also induced haematological changes such as an increased level of total bilubrin, amylase and glutamic-oxalacetic transaminase and decrease of cholinesterase activity, indicating damage of the liver and nervous system in rats.
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  • 46
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A direct, isocratic and simple liquid chromatographic method is described for the enantiomeric separation of propafenone (PRO) and its major metabolite, 5-hydroxypropafenone, using a cellulose tris-3,5-dimethylphenyl carbamate (Chiralcel ODS) column. The sterochemical separation factor (α) obtained was 1.14 and the maximum stereochemical resolution factor (R) was 0.80 when using a mobile phase consisting of hexane: 2-propanol: diethylamine (90:10:0.4) at 23°C. The hydroxy metabolite could not be successfully separted into its corresponding enantiomers under these chromatographic conditions. The method has been used to determine and identify the enantiomers of PRO and its hydroxy metabolite in a serum sample.
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  • 47
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Novel fluorogenic Edman reagents, 7-N,N-dimethylaminosulphonyl-4-(2,1,3-benzoxadiazolyl)isothiocyanate (DBD-NCS) and 7-aminosulphonyl-4-(2,1,3-benzoxadiazolyl)isothiocyanate (ABD-NCS) having no fluorescence themselves were synthesized. The derivatives of amino acids with DBD-NCS fluoresce at 505 nm with excitation at 385 nm. They were separated on a reversed-phase HPLC column and detected at the sub-picomol level. Ala-Phe derivatized with DBD-NCS was cleaved by acid to generate DBD-thiocarbamyl-Ala.
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  • 48
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    Biomedical Chromatography 7 (1993), S. 162-165 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A high performance liquid chromatographic (HPLC) procedure for measuring pyridoxal-5′-phosphate (PLP) and certain forms of B6 vitamers in plasma is presented here. This HPLC procedure consisted of a single graphitic carbon column with a fluorescence detector employing an isocratic eluent (15% acetonitrile:1% perchloric acid: 0.05% sodium bisulfite). The graphitic carbon column is useful in acidic eluent without deteriorization. The relatively low fluorescent intensity of PLP under acidic conditions is improved by its derivatization with bisulfite in the eluent during chromatographic separation. Using this procedure, the detection limit of PLP is 50 fmol, and an aliquot of 5-50 μL of human plasma is required giving satisfactorily precise results within 5 min. We applied this method to the determination of PLP and certain B6 vitamers in human plasma after oral supplementation of pyridoxine.
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  • 49
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    Biomedical Chromatography 7 (1993), S. 126-128 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A rapid and simple high performance liquid chromatographic analytical method is described for the simultaneous determination of norfloxacin and furprofen in rat plasma. Following dichloromethane extraction, the solution was chromatographed in a Vydac anion exchange column using a mobile phase of 0.05 M phosphate buffer (pH=7.0):acetonitrile (80:20, v/v) at a flow-rate of 1.8 mL/min. The drugs were detected by UV absorption at 278 nm. The total chromatographic analysis time was 10 min. The response was linear, 0.1-5.0 μg/mL for norfloxacin and 0.1-3.0 μg/mL for furprofen, respectively. This method is useful for pharmacokinetic studies of these compounds and will facilitate detailed investigations into the interactions between quinolones and furprofen.
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  • 50
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: We have studied the metabolism (absorption) of β-carotene and vitamin E by assigning eleven volunteers to receive daily two capsules of OENOBIOL, each containing 15 mg of β-carotene and 15 mg of vitamin E, over 60 days. The β-carotene, vitamin E and vitamin A plasma levels were then determined using new methods developed in our laboratory. After two months, the actively treated group's median β-carotene and vitamin E levels were significantly higher than those of a control group. However, no significant change between treated and control groups in the mean of vitamin A (retinol) plasma levels were observed. Treatment with β-carotene, a vitamin A precursor, does not significantly modify the vitamin A levels. This conclusion had already been observed and it is assumed that a plasma level of β-carotene equal or higher than 0.3 mg/L reflects a nutritional intake of provitamins sufficient to support homeostasis of retinol (Brubacher et al., 1982).
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  • 51
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    Biomedical Chromatography 7 (1993), S. 119-119 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 52
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    Biomedical Chromatography 7 (1993), S. 134-135 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A high performance liquid chromatographic assay for the quantitation of acetazolamide in both tablet and injection form is described. Acetazolamide is extracted with 0.005 M NaOH solution containing 0.3 mg/mL sulphadiazine (internal standard).A commercially available μ-Bondapak C18 cartridge column was used for the separation together with a mobile phase made of acetonitrile, methanol and sodium acetate buffer mixture (10:2:88) (pH 4) at a flow-rate of 4 mL/min. Retention times of about 2.50 and 3.36 min were obtained for the drug and the internal standard, respectively.
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  • 53
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    Biomedical Chromatography 7 (1993), S. 146-148 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A separation to the baseline isocratic technique has been developed for the evaluation of the purity of aprotinin by internal normalization. The column used was a 30 nm pore diameter butyl-bonded silica stationary phase. An exact relationship was found to give an adequate description of the retention of aprotinin using acetonitrile concentrations of 17-22% and NaCIO4 concentrations of 5-50 mmol. It can be used to optimize the mobile phase content for the particular user column and to compensate for possible variations in the retention time of aprotinin, analysed on different batches of butyl-bonded stationary phases.
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  • 54
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    Biomedical Chromatography 7 (1993), S. 180-180 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 55
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A rotating flow mixing device having three directional inlets was developed for a high performance liquid chromatographic peroxyoxalate chemiluminescence detection system for the sensitive detection of fluorescent compounds separated with acidic mobile phases, such as those containing trifluoroacetic acid. The diameters of the three inlets were 0.3, 0.3 and 0.5 mm i.d., for an acidic column eluate, chemiluminogenic reagents (bis[4-nitro-2-(3,6,9-trioxadecyloxycarbonyl)phenyl] oxalate and hydrogen peroxide) and imidazole solution (for neutralization and as a catalyst), respectively. The three mixed solutions flowed out through an outlet (0.5 mm i.d.) at the centre of the top of the vessel. The reaction conditions to give the appropriate signal-to-noise ratio (S/N) were investigated using dipyridamole (an antiplatelet aggregation drug) as a typical fluorescent compound. The system was applied to the detection of dipyridamole and dansylated amino acids with a mobile phase containing trifluoroacetic acid. The detection limits for dipyridamole and each dansylated amino acid were 10 amol and sub-fmol (S/N=2), respectively.
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  • 56
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    Biomedical Chromatography 7 (1993), S. 311-314 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: An isocratic reversed-phase high performance liquid chromatographic method for the determination of tamoxifen and its metabolites in plasma and tissues is described. Plasma or tissue homogenate was extracted with methanol/dimethyl sulphoxide (4:1 v/v). The supernatant after centrifugation was separated on a BDS-Hypersil column with methanol/0.5 M ammonium acetate (75:25 v/v) as the mobile phase. The recoveries of tamoxifen added to plasma and liver tissue homogenate by the extraction procedure were 102± 1.6 and 98±2.4% (mean±SD, n = 6), respectively. The solutes were detected at 280 nm with a detection limit of 0.25 μg/mL for tamoxifen.
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  • 57
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    Biomedical Chromatography 7 (1993), S. 317-320 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A method for the preparation of a new packing material for high performance liquid chromatography by bonding an anti-interferon monoclonal antibody to the surface of silica gel is described. The high coupling efficiency and activity of the interferon-αA-monoclonal antibody (IFN-αA-McAb) column were obtained by activated diol-silica gel with an activating agent. After purification with this packing material, the specific activity of recombinant human interferon-αA rose by up to 1.03 × 107IU/mg protein and the purification efficiency was increased by approximately 100 times.
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  • 58
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A high performance liquid chromatographic (HPLC) method with fluorescence detection after on-line reduction for the determination of 1-nitropyrene (NP), 1-nitrosopyrene (NSP), 1-aminopyrene (AP) and N-acetylaminopyrene (AAP) has been developed. The reduction efficiency of NP and NSP on a zinc column was found to be higher than that of an electrochemical reducer. Using a HPLC equipped with a zinc column (4.0 mm i.d. × 10 mm) and an imidazole/HCIO4 (pH 6.8):acetonitrile mobile phase, detection limits (S/N = 3) of 20-30 fmol for NP, NSP and AP and 350 fmol for AAP were obtained. NP, NSP and AP were determined in the incubation mixture of NP and Salmonella typhimurium, YG1021, by this method. Time course studies showed that a large ratio of NP was metabolized in the pre-incubation step of the Ames test.
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  • 59
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    Biomedical Chromatography 7 (1993) 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 60
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    Biomedical Chromatography 7 (1993), S. 301-305 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The metabolic fate of fenitrothion, O,O-dimethyl-O-(3-methyl-4-nitro phenyl) phosphorothioate, was investigated in rat tissues during the first 24 hours following the intramusculer administration of the pesticide in the animal. High performance liquid chromatography (HPLC) of the pesticide and its metabolites formed in liver, kidney and brain showed the time-dependent sequential conversion of the pesticide into three major metabolites. These metabolites were separated and purified to homogeneity by HPLC and characterized by IR spectroscopy as O,O-dimethyl-O-)3-methyl-4-aminophenyl) phosphorothioate (metabolite I), O,O-dimethyl phosphorothioate (metabolite II), and O,O-dimethylphosphate (metabolite III). These results indicated reduction of the nitro group in fenitrothion aas the first step, followed by the hydrolytic cleavage of the P-O-aryl bond in metabolite I and the oxidative desulphurylation of metabolite II. Fenitrothion was found to induce ultrastructural changes in liver cells especially after 12 h exposure nuclear membrane was completely distorted, nuclear intactness was totally lost and smooth endoplasmic reticulum and Golgi apparatus were abnormally enlarged. In 24 h, however, the regeneration of the nuclear material was observed.
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  • 61
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A selective and sensitive method for the determination of free and total proline (Pro) and 4-hydroxyproline (Hyp) by gas chromatography (GC) was developed. For free Pro and Hyp analysis, plasma and tissue homogenate were extracted with methanol. For total Pro and Hyp analysis, these samples were hydrolysed in 6 M HCI. After removal of primary amino compounds by the reaction with o-phthaldialdehyde, Pro and Hyp in methanol extract and acid hydrolysate were converted into their N-dimethylthiophosphoryl methyl ester derivatives and then determined by GC with flame photometric detection using a DB-5 capillary column. This method was successfully applied to small samples without prior clean-up, and Pro and Hyp in these samples could be analysed without any influence from coexisting substances. Overall recoveries of Pro and Hyp added to plasma and tissue samples were 92-106%. The analytical results of free and total Pro and Hyp in human plasma and mouse tissue samples are presented.
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  • 62
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    Biomedical Chromatography 7 (1993), S. 315-316 
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A simple and sensitive (up to nanogram level) method to determine norepinephrine, serotonine and dopamine in rat brain is described. The amines are acetyled and the derivatives are resolved by thin layer chromatography (TLC) on silica high performance thin layer chromatography (HPLC) plates. Quantification is achieved by fluorescence densitometry at 415 nm excitation wavelength.
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  • 63
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    Journal of Chemometrics 7 (1993), S. 75-76 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 64
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 65
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    Journal of Chemometrics 7 (1993), S. 243-253 
    ISSN: 0886-9383
    Keywords: Orthogonal expansion ; Mapping ; Modelling ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this paper we discuss the orthogonal expansion of data matrices and its application to mapping and modelling. Two new methods, modified optimal discriminant plane (MODP) for mapping and order Gram-Schmidt orthogonalization (OGSO) for modelling, are proposed and examples are given.
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  • 66
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    Journal of Chemometrics 7 (1993) 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 67
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    Journal of Chemometrics 7 (1993), S. 381-392 
    ISSN: 0886-9383
    Keywords: Factor analysis ; Kolmogorov-Smirnov test ; Non-parametric tests in factor analysis ; Non-parametric test for principal components ; Principal component analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Each eigenvector of the dispersion matrix [X]T [X] was shown to be a partial predictor of the original data matrix [X], the sum of the predictions from the individual principal components being equal to the expectance of [X]. By comparing the distributions of the members of two neighbouring predicted matrices, [X̃]1…i and [X̃]1…i+1 (i.e. the sums of the first i and i + 1 individual predictions respectively), it was shown that they should be indistinguishable provided that i is equal to or greater than the effective rank of [X], and significantly different otherwise. This was confirmed by analysing the visible absorption spectra of methyl orange and methyl red solutions as well as the Raman spectra of Na2SO4 and MgSO4 solutions. On the grounds of these findings, a non-parametric goodness-of-fit test for assessing the effective rank of [X] was proposed which proved to be comparatively conservative and more robust than most currently used tests.
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  • 68
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    Journal of Chemometrics 7 (1993), S. 369-379 
    ISSN: 0886-9383
    Keywords: Simulated annealing ; Constrained background bilinearization ; Calibration ; Two-way bilinear data ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Generalized simulated annealing (GSA) is an optimization technique for locating the global optimum. In this paper GSA was used as the optimization procedure in the constrained background bilinearization (CBBL) of two-way bilinear data in order to reduce the possibility of sinking into local optima. The behaviour of the algorithm and its comparison with the modified Powell algorithm were studied by simulations and real fluorescence excitation-emission data for organic dye mixtures.
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  • 69
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    Journal of Chemometrics 7 (1993), S. 439-445 
    ISSN: 0886-9383
    Keywords: Calibration ; Rank annihilation ; Residual bilinearization ; Three-way ; Trilinear ; Net analyte rank ; Second-order ; Generalized rank annihilation method (GRAM) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Through theoretical analysis and computer simulation, this short communication comments on the residual bilinearization (RBL) method and compares it with non-bilinear rank annihilation (NBRA) for the treatment of second-order calibration with non-bilinear data. It is found that these two methods are mathematically equivalent but have different noise propagation properties. The second-order advantage, namely quantitation in the presence of unknown interferences, can be carried over to non-bilinear data only if there exists a net analyte rank (NAR) for the analyte of interest.
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  • 70
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    Journal of Chemometrics 7 (1993), S. 495-526 
    ISSN: 0886-9383
    Keywords: Standard errors ; Eigenvalues ; PCA ; MLR ; GRAM ; Rank estimation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New expressions are derived for the standard errors in the eigenvalues of a cross-product matrix by the method of error propagation. Cross-product matrices frequently arise in multivariate data analysis, especially in principal component analysis (PCA). The derived standard errors account for the variability in the data as a result of measurement noise and are therefore essentially different from the standard errors developed in multivariate statistics. Those standard errors were derived in order to account for the finite number of observations on a fixed number of variables, the so-called sampling error. They can be used for making inferences about the population eigenvalues. Making inferences about the population eigenvalues is often not the purposes of PCA in physical sciences. This is particularly true if the measurements are performed on an analytical instrument that produces two-dimensional arrays for one chemical sample: the rows and columns of such a data matrix cannot be identified with observations on variables at all. However, PCA can still be used as a general data reduction technique, but now the effect of measurement noise on the standard errors in the eigenvalues has to be considered. The consequences for significance testing of the eigenvalues as well as the usefulness for error estimates for scores and loadings of PCA, multiple linear regression (MLR) and the generalized rank annihilation method (GRAM) are discussed. The adequacy of the derived expressions is tested by Monte Carlo simulations.
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  • 71
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    Journal of Chemometrics 7 (1993), S. 559-566 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 72
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    Journal of Chemometrics 7 (1993) 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 73
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    Journal of Chemometrics 7 (1993), S. 61-73 
    ISSN: 0886-9383
    Keywords: Compression ; Multivariate analysis ; B-splines ; Maximum entropy ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: For efficient handling of very large data arrays, pretreatment by compression is mandatory. In the present paper B-spline methods are described as good candidates for such data array compression. The mathematical relation between the maximum entropy method for compression of data tables and the B-spline of zeroth degree is described together with the generalization of B-spline compression to nth-order data array tables in matrix and tensor algebra.
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  • 74
    ISSN: 0886-9383
    Keywords: Factor analysis ; Window factor analysis ; Multicomponent analysis ; Ultraviolet spectroscopy ; Cu(II) complexes ; Ethylenediaminetetraacetic acid ; EDTA ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Window factor analysis (WFA) is a self-modeling chemometric technique for obtaining the concentration profiles of components from evolutionary processes such as chromotography, titration and reaction kinetics. By specifying the ‘window’, i.e. the region along the evolutionary axis indigenous to a component, the concentration profile of the component can be obtained without recourse to any information concerning the other components. Mathematical expressions required to perform such computations are derived. The method is applied to the investigation of copper(II) complexation with ethylenediaminetetraacetate (EDTA) by recording and factor analyzing the ultraviolet spectra of aqueous solutions containing a fixed amount of the disodium salt of EDTA and varying amounts of CuCl2. Evidence for four different species of EDTA is obtained. Clues concerning the stoichiometry of the species are garnered from the concentration profiles.
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  • 75
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    Journal of Chemometrics 7 (1993), S. 131-142 
    ISSN: 0886-9383
    Keywords: Classification ; Discriminant analysis ; Class modeling ; Specification limits ; Cross-validation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: There are many chemical products where product conformity is decided upon by qualitative human judgements of overall product quality. Nowadays, quantitative instrumentally determined quality parameters become available which are intended to replace such qualitative judgements by means of automatic decision rules using multivariate specification limits. Six classification methods to derive such limits are compared in terms of their power to predict corresponding human judgemets on overall color conformity of 17 dyestuffs based on historical quality data. Standard statistical classification methods turned out to be unacceptable for the routine generation of decision rules because of the frequent distinct suboptimality of their predictive power. Instead, a simple non-statistical classification method utilizing a priori knowledge about the underlying data structure yielded uniformly satisfactory decision rules.
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  • 76
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    Journal of Chemometrics 7 (1993), S. 153-163 
    ISSN: 0886-9383
    Keywords: Generalized inverse ; K-matrix analysis ; P-matrix analysis ; Least squares ; Principal component regression ; Partial least squares ; Continuum regression ; Beer's law ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper consists of two distinct but related parts. In the first part a geometric theory of generalized inverses is presented and a methodology based on this theory is developed and applied to solve the K-matrix and P-matrix forms of Beer's law. It is shown that most currently accepted and practiced methods for solving these forms of Beer's law are just special cases of this geometric theory of generalized inverses. In addition, this geometric theory is used to explain why the current methods work and why they fail.In the second part a general methodology that includes as special cases least squares, principal component regression, partial least squares 1 and 2, continuum regression plus a variety of other described and undescribed methodologies is presented and then applied to solve the P-matrix formulation of Beer's law. This general methodology, like the first, is also geometric in nature and relies on an understanding of projections.The main emphasis of this paper is one of perspective, which, if understood, provides the proper foundation for answering the general but extremely hard and possibly unanswerable question “what is the best method?”.
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  • 77
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    Journal of Chemometrics 7 (1993), S. 195-212 
    ISSN: 0886-9383
    Keywords: Calibration ; Non-linearity ; Principal components ; Stein estimate ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new regression method for non-linear near-infrared spectroscopic data is proposed. The technique is based on a model which is linear in the principal components and simple functions (squares and products) of them. Added variable plots are used to determine which squares and products to incorporate into the model. The regression coefficients are estimated by a Stein estimate which shrinks towards the estimate determined by the first several principal components and the selected non-linear terms. The technique is not computationally intensive and is appropriate for routine predictions of chemical concentrations. The method is tested on three data sets and in all cases gives more accurate predictions than does linear principal components regression.
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  • 78
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    Journal of Chemometrics 7 (1993), S. 227-242 
    ISSN: 0886-9383
    Keywords: Non-linear mapping ; Graphical methods ; SAR ; SPR ; Quality of representation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: From a review of the theoretical aspects of non-linear mapping and the different algorithms available in the literature, the methodological and practical problems linked to the use of this multivariate method in structure-activity and structure-property relationship studies are underlined. Useful tools for the graphical display of the outputs and the interpretation of the obtained clusters are presented. Statistical parameters estimating the quality of the graphical representation of each individual are also introduced. An example of application on a data matrix of 37 acaricides described by four physicochemical descriptors (π, F, R, MR) is presented.
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  • 79
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    Journal of Chemometrics 7 (1993), S. 291-304 
    ISSN: 0886-9383
    Keywords: Partial least squares ; Monte Carlo methods ; Cross validation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Partial least squares (PLS) regression is a commonly used statistical technique for performing multivariate calibration, especially in situations where there are more variables than samples. Choosing the number of factors to include in a model is a decision that all users of PLS must make, but is complicated by the large number of empirical tests available. In most instances predictive ability is the most desired property of a PLS model and so interest has centred on making this choice based on an internal validation process. A popular approach is the calculation of a cross-validated r2 to gauge how much variance in the dependent variable can be explained from leave-one-out predictions. Using Monte Carlo simulations for different sizes of data set, the influence of chance effects on the cross-validation process is investigated. The results are presented as tables of critical values which are compared against the values of cross-validated r2 obtained from the user's own data set. This gives a formal test for predictive ability of a PLS model with a given number of dimensions.
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  • 80
    ISSN: 0886-9383
    Keywords: Reaction kinetics ; Initial rate ; Kinetic order ; Response surface modelling ; Canonical analysis ; Organic synthesis ; Optimization ; Reaction mechanisms ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method is presented by which it is possible to estimate the initial rate of chemical reactions when the experimental conditions are varied according to a response surface design. The method is intended as a complementary method for analysing data obtained from experiments in synthetic chemistry when the objective is to optimize the yield of the reaction.Data obtained by simulations have been used to develop the method. From the simulated reactions it is shown that sequential analysis of the chemical yield of the reaction makes it possible to estimate models which describe how the parameters of the response surface of the yield vary over time. The derivatives of these time functions of the response surface parameters can be used to define a rate function which describes how the variations in the experimental conditions influence the rate of the reaction.It is shown how such rate functions can be used to afford reasonable estimates of the initial rates of the reaction. The initial reaction rates thus estimated can be used to determine the kinetic order of the reactants and also to provide estimates of the activation energy of the reaction.A thorough discussion of how canonical analysis of the rate function may assist in the elucidation of reaction mechanisms is given.
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  • 81
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    Journal of Chemometrics 7 (1993), S. 427-438 
    ISSN: 0886-9383
    Keywords: Quality control ; Kerosene ; Variable reduction ; Cross-validation ; Variable selection ; Procrustes rotation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper deals with a typical question encountered in all industrial analytical laboratories: are all the tests performed in the laboratory to characterize the final product really necessary? In this work the cross-validation technique, Procrustes rotation techniques and statistical variable selection have been used to reduce the 26 initial British Petroleum and ASTM kerosene specification test to ten ‘essential’ ones. Statistical as well as chemical considerations were used to select the optimum subset of original variables to be retained from all the possible ones.
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  • 82
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    Journal of Chemometrics 7 (1993), S. 453-454 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 83
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    Journal of Chemometrics 7 (1993), S. 527-541 
    ISSN: 0886-9383
    Keywords: Principal component analysis ; Projection pursuit ; Simulated annealing algorithm ; Robust statistics ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Principal component analysis (PCA) is a widely used technique in chemometrics. The classical PCA method is, unfortunately, non-robust, since the variance is adopted as the objective function. In this paper, projection pursuit (PP) is used to carry out PCA with a criterion which is more robust than the variance. In addition, the generalized simulated annealing (GSA) algorithm is introduced as an optimization procedure in the process of PP calculation to guarantee the global optimum. The results for simulated data sets show that PCA via PP is resistant to the deviation of the error distribution from the normal one. The method is especially recommended for use in cases with possible outlier(s) existing in the data.
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  • 84
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    Journal of Chemometrics 7 (1993), S. 45-59 
    ISSN: 0886-9383
    Keywords: Partial least squares ; PLS algorithm ; Kernel ; Multivariate image analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A fast and memory-saving PLS regression algorithm for matrices with large numbers of objects is presented. It is called the kernel algorithm for PLS. Long (meaning having many objects, N) matrices X (N × K) and Y (N × M) are condensed into a small (K × K) square ‘kernel’ matrix XTYYTX of size equal to the number of X-variables. Using this kernel matrix XTYYTX together with the small covariance matrices XTX (K × K), XTY (K × M) and YTY (M × M), it is possible to estimate all necessary parameters for a complete PLS regression solution with some statistical diagnostics. The new developments are presented in equation form. A comparison of consumed floating point operations is given for the kernel and the classical PLS algorithm. As appendices, a condensed matrix algebra version of the kernel algorithm is given together with the MATLAB code.
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  • 85
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    Journal of Chemometrics 7 (1993), S. 77-88 
    ISSN: 0886-9383
    Keywords: Direct trilinear decomposition method ; Curve resolution ; Trilinear data ; Similarity transformation ; Generalized rank annihilation method ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The direct trilinear decomposition method (DTDM) is an algorithm for performing quantitative curve resolution of three-dimensional data that follow the so-called trilinear model, e.g. chromatography-spectroscopy or emission-excitation fluorescence. Under certain coditions complex eigenvalues and eigenvectors emerge when the generalized eigenproblem is solved in DTDM. Previous publications never treated those cases. In this paper we show how similarity transformations can be used to eliminate the imaginary part of the complex eigenvalues and eigenvectors, thereby increasing the usefulness of DTDM in practical applications. The similarity transformation technique was first used by our laboratory to solve the similar problem in the generalized rank annihilation method (GRAM). Because unique elution profiles and spectra can be derived by using data matrices from three or more samples simultaneously, DTDM with similarity transformations is more efficient than GRAM in the case where there are many samples to be investigated.
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    Journal of Chemometrics 7 (1993), S. 143-148 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Journal of Chemometrics 7 (1993), S. 151-151 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 88
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    Journal of Chemometrics 7 (1993), S. 213-222 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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  • 89
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 90
    ISSN: 0886-9383
    Keywords: Multicomponent analysis ; Factor analysis ; Detection limit ; Local rank ; Zero-component region ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this paper we redefine the term detection limit to embrace the inherent multivariate nature of samples, instrumental measurements and chemometrics resolution procedures. The so-called zero-component regions, i.e. parts with no chemical components eluting, are used as repeated analytical blanks to estimate a statistical multivariate detection limit for determining the number of chemical species in local regions of a single two-way chromatogram or a collection of synchronized one-way chromatograms. For two-way chromatography the detection limit is determined from the distribution of the first eigenvalues obtained from all possible combinations of spectra in the zero-component regions. The number of spectra in each calculation should correspond to the number included in the later examination of the local retention time regions. For one-way chromatography on a collection of samples with similar chemical components at varying concentrations the same procedure is used, with the samples taking the role of the spectra in two-way chromatography. The detection limit can be chosen at various confidence levels depending on whether false positive or negative detection of minor components is most critical. The results obtained from the zero-eigenvalue distribution are more robust than those obtained by a previously developed F-test.
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  • 91
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    Journal of Chemometrics 7 (1993), S. 447-452 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 92
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    Journal of Chemometrics 7 (1993), S. 477-494 
    ISSN: 0886-9383
    Keywords: Three-way principal components analysis ; Core matrix ; Body diagonalization ; Lower and upper bounds ; Simulation ; Soil contamination ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In contrast with conventional PCA, a direct superposition and joint interpretation of loading plots is not possible in three-way PCA, since there may be data variance which is described by unequal components of different modes. The contributions to variance of all possible combinations of components are described in the core matrix. Body diagonalization, which is achieved by appropriate rotation of component matrices, is an essential tool for simplifying the core matrix structure. The maximum degree of body diagonality which may be obtained from such transformations is analysed from both the mathematical and simulation viewpoints. It is shown that, at least in the average case, high degrees can be expected, which makes the procedure reasonable for many practical applications. Furthermore, simulation as well as theoretical derivation show that the success of body diagonality depends on the so-called polarity of the core array. The methodology is illustrated by a three-way data example from environmental chemistry.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 93
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 7 (1993), S. 551-557 
    ISSN: 0886-9383
    Keywords: Krylov sequence ; Partial least squares ; Polynomial regression ; Principal component regression ; R2 ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: PLS1 regression is generally viewed as lying in between PCR and OLS regression. Proof is given that the coefficient of determination, R2, for a PLS multivariate calibration model is at least as high as that for a PCR model with the same number of components. It appears that PLS can be linked to a correlation-weighted polynomial regression of a constant response on the eigenvalues of the covariance matrix of the predictor variables.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 94
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 7 (1993), S. 1-14 
    ISSN: 0886-9383
    Keywords: Continuum regression ; Dynamic model identification ; Principal component regression ; Partial least squares regression ; Finite impulse response ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The use of continuum regression (CR) for the identification of finite impulse response (FIR) dynamic models is investigated. CR encompasses the methods of principal component regression (PCR), partial least squares (PLS) and multiple linear regression (MLR). PCR and MLR are at the two extremes of the continuum. In PCR and PLS, cross-validation is used to determine the optimum number of factors or ‘latent variables’ to retain in the regression model. CR allows one to vary the method in addition. Cross-validation then determines both the optimum method and the number of latent variables. The CR ‘prediction error surface’ - a function of the method and number of latent variables - is elucidated. The optimal model is defined as the minimum of this surface. Among the cases studied, the optimal model usually comes from the region of the continuum between PCR and PLS. Few derive from the region between PLS and MLR. It is also demonstrated that FIR models identified by CR have frequency domain properties similar to those identified by PCR.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 95
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 7 (1993) 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 96
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 7 (1993), S. 117-130 
    ISSN: 0886-9383
    Keywords: Calibration ; Rank annihilation ; Three-way ; Trilinear ; Bilinear ; Non-bilinear ; Net analyte signal ; MS/MS ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several multivariate methods are now available for the calibration of second-order or hyphenated instruments (e.g. GC/MS). When applied to bilinear data, it has been shown that calibration can be performed in the presence of unknown interferences - a significant advantage over first-order calibration. In this paper, non-bilinear rank annihilation (NBRA), a method which has the potential of handling, second-order non-bi-linear data, is studied through theoretical analysis and computer simulation. It is found that the second-order advantage can be carried over to non-bilinear data if a property defined as net analyte rank (NAR) holds for the analyte of interest. The net analyte signal (NAS) is defined accordingly for second-order calibration and the analogy to and difference from lower-order calibration are discussed. With NAS, some analytical figures of merit such as signal-to noise ratio, selectivity, sensitivity and limit of determination can be calculated for second order calibration. An application to MS/MS data is also given.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 97
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 7 (1993) 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 98
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 7 (1993), S. 177-193 
    ISSN: 0886-9383
    Keywords: Multivariate analysis ; Function space ; Coefficient space ; B-splines ; Compression ; PCA ; PLS ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A general framework for manipulating spectra as functions in traditional multivariate methods such as PCA and PLS is described. The functional representation is very convenient for compression, ensuring smoothness and continuity. There are two fundamentally different types of representations: (a) by functions and (b) by function coefficients. The use of coefficients is the most practical way of analysis.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 99
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 100
    ISSN: 0886-9383
    Keywords: Kalman filter ; Multivariate calibration ; Condition number ; Prediction error ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The usefulness of the Kalman filter as an algorithm for calibration in a real system is shown. Results are compared with classical least squares and pure component calibration. The prediction of four priority pollutant chlorophenols in binary, ternary and quaternary mixtures was also carried out by Kalman filtering. The condition number, standard deviation and prediction error have been employed to choose the most suitable wavelength range. Comparison of the standard error of prediction in the validation set shows significant differences between the evaluated chlorophenols, the best results being obtained with Kalman multivariate calibration.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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