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  • 1990-1994  (2,279)
  • 1992  (2,279)
  • Analytical Chemistry and Spectroscopy  (1,522)
  • Engineering  (757)
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  • 1990-1994  (2,279)
Year
  • 101
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 231-246 
    ISSN: 0886-9383
    Keywords: Integration methods ; Taylor series method ; Optimization methods ; Kinetic mechanisms ; Kinetic determinations ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A general equation to derive kinetic models up to any order is given. This equation greatly facilitates the application of the Taylor series method to the integration of kinetic models up to very high orders. When dealing with non-stiff models, computing time is always reduced by increasing the integration order, at least up to the 20th order. When the model is stiff, the integration order should be optimized; however, a twelfth order is recommended to integrate weakly stiff models. The use of an algorithm which permits the immediate calculation of the integration step size required to maintain a given accuracy leads to further reductions in computing time. When implemented as recommended here, a high-order Taylor series method is more rapid and accurate than Runge-Kutta and predictor-corrector methods and can be advantageously used in combination with optimization methods to perform mechanism studies and in multicomponent kinetic determinations.
    Additional Material: 6 Ill.
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  • 102
    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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  • 103
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 289-305 
    ISSN: 0886-9383
    Keywords: Chemical structure database ; Conformational searching ; Similarity searching ; Substructure searching ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper presents a review of the rapid developments that have taken place over the last few years for the searching of databases of three-dimensional (3D) molecules. The geometric arrangement of the atoms in a 3D molecule is described by an interatomic distance matrix. This is a form of labelled graph that can thus be searched using the subgraph-isomorphism algorithms that are widely used for searching databases of two-dimensional (2D) molecules. Several in-house and commercial systems have been developed for 3D database searching that are based on such techniques. These systems are reviewed and their effectiveness demonstrated by examples of their use in the discovery of novel, biologically active molecules. Current systems represent a molecule by one or a small number of low-energy conformations and there is hence much interest in the development of representational techniques and searching algorithms that account for the full set of geometric arrangements that can be adopted by a flexible molecule.
    Additional Material: 1 Ill.
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  • 104
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992) 
    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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  • 105
    ISSN: 0886-9383
    Keywords: GOLPE ; PLS ; Regression ; SDEP ; Variable selection ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A procedure called GOLPE is suggested in order to detect those variables which increase the predictivity of PLS models. The procedure is based on evaluating the predictive power of a number of PLS models built by different combinations of variables selected according to a factorial design strategy. Examples are given of the efficiency of this variable selection procedure, which shows how these predictive PLS models are better than those obtained by all variables and better than the corresponding ordinary regression models.
    Additional Material: 3 Ill.
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  • 106
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 11-28 
    ISSN: 0886-9383
    Keywords: Three-way PLS ; PARAFAC ; Unfolding ; Validatory tools ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The methods PARAFAC and three-way PLS are compared with respect to their ability to predict reversed-phase retention values. Special attention is paid to simple validatory tools, the meaning and use of which are explained.
    Additional Material: 12 Ill.
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  • 107
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 41-56 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The principal properties, here called the ρ-scales, of peat have been calculated on the basis of chemical analysis. The scales were derived from quantitative contents of carbohydrates, Klason lignin, amino acids, amino sugars and conventional chemical peat measurements. The variation in the chemical parameters was compressed using principal component analysis (PCA). Partial least squares (PLS) regression was used for prediction of botanical, microbial, physical and dewatering data. A rapid estimation of the scales has been made from near-infrared (NIR) spectroscopy and offers, indirectly, rapidly obtainable, chemically interpretable, biological information. A reduced scale based on carbohydrate data was also tested. The ρ-scales offer an interface between different areas of peat research. Strategies are outlined for the selection of a subset of chemical measurements among the variables used for characterization. A multivariate strategy based on these ideas is discussed.
    Additional Material: 13 Ill.
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  • 108
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992) 
    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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  • 109
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 217-225 
    ISSN: 0886-9383
    Keywords: Principal component regression ; Calibration ; Optimality ; Principal component selection ; Quantitative structure-activity relationship ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Principal components (PCs) for principal component regression (PCR) have historically been selected from the top down for a reliable predictive model. That is, the PCs are arranged in a list starting with the most informative (PC associated with the largest singular value) and proceeding to the least informative (PC associated with the smallest singular value). PCs are then chosen starting at the top of this list. This paper discusses an alternative procedure of treating PC selection as an optimization problem. Specifically, without any regard to the ordering, the optimal subset of PCs for an acceptable predictive model is desired. Five data sets are analyzed using the conventional and alternative approaches. Two data sets are spectroscopic in nature, two data sets deal with quantitative structure-activity relationships (QSARs) and one data set is concerned with modeling. All five data sets confirm that selection of a subset without consideration to order secures the best results with PCR. One data set is also compared using partial least squares 1.
    Additional Material: 7 Tab.
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  • 110
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. i 
    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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  • 111
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 257-266 
    ISSN: 0886-9383
    Keywords: Principal factor analysis ; Factor analysis ; Eigenvalue analysis ; Multivariate analysis ; Weighted factor analysis ; Procrustean analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two approximate methods for weighted principal components analysis (WPCA) were devised and tested in numerical experiments using either empirical variances (obtained from replicated data) or assumed variances (derived from unreplicated data). In the first (‘spherical’) approximation each data vector was assigned a weight proportional to the geometrical mean of its variances in all dimensions. The arithmetical mean of variances was used instead in the other approximation. Both the numerical experiments with artificial data containing random errors of various kinds (constant, proportional, constant plus proportional, Poisson) and the analysis of two sets of Raman spectra clearly indicated the necessity of introducing statistical weights. The spherical approximation was found to be slightly better than the arithmetical one. The application of statistical weighting was found to improve the performance of PCA in estimation problems.
    Additional Material: 3 Ill.
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  • 112
    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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  • 113
    ISSN: 0886-9383
    Keywords: Predictive ability ; Regression ; PLS ; SDEP ; Cross-validation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The standard deviation of prediction errors (SDEP) is used to evaluate and compare the predictive ability of some regression models, namely MLR, ACE and linear and non-linear PLS, the last being the best one. The parameter is determined by a cross-validation approach as an average of several runs obtained on forming groups in a random way. The variation in SDEP with the number of latent variables in PLS is also discussed.
    Additional Material: 3 Ill.
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  • 114
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 840-842 
    ISSN: 0935-6304
    Keywords: UV detection ; Fluorescence detection ; FID ; Mass spectrometry ; Air pollution ; Chlorine ; 1-Chloro-2-naphthol ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 115
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 827-833 
    ISSN: 0935-6304
    Keywords: GC ; Lubricating Oil ; Polycyclic aromatic hydrocarbons (PAH) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Liquid - liquid extraction with N-methyl-2-pyrrolidone, combined with solid-phase extraction on silica gel using n-pentane and dichloromethane as solvents, has been used for the isolation and concentration of the aromatic fraction from lubricating oil.The identification of individual compounds in this aromatic fraction was performed by capillary gas chromatography-mass spectrometry (CGC-MS) and by determination of retention indices. Quantitative results were obtained by flame ionization detection (CGC-FID). Eighty four compounds, predominantly naphthalenes, phenanthrenes, biphenyls, fluorenes, dibenzo-thiophenes, and their alkylated derivatives, have been identified in a commercial lubricating oil. The total amount of the aromatic fraction did not exceed 0.04 % of the oil.
    Additional Material: 2 Ill.
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  • 116
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 834-836 
    ISSN: 0935-6304
    Keywords: Static headspace ; Optimization of conditions ; Gas chromatography ; Blood alcohol ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The precision and sensitivity of head-space GC can be improved by careful selection of the operating conditions: partitioning in the vapor phase can be promoted by altering the sample matrix; the ratio of the volumes of the gaseous and liquid phases, the sample temperature, the equilibration time, and the effect of sample mixing should also be considered.Most of the principles covered here can be applied to either manual headspace GC or to headspace GC utilizing an automated sampler.
    Additional Material: 5 Ill.
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  • 117
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 30-32 
    ISSN: 0935-6304
    Keywords: Capillary zone electrophoresis ; Ionization constants ; Aromatic amines ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Capillary zone electrophoresis in untreated fused silica capillaries has proved suitable for the determination of the ionization constants of weak electrolytes. Several fundamental equations relating the electrophoretic mobilities of ionized solutes to hydronium ion concentrations in the running electrolyte have been verified experimentally. The observed dependence of the electrophoretic mobilities of weak bases and ampholytes on the pH of the electrolyte showed good agreement with predicted behavior. The pKa values calculated from electrophoretic mobility data obtained by capillary zone electrophoresis were reasonably close to those reported in the literature.
    Additional Material: 2 Ill.
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  • 118
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 36-39 
    ISSN: 0935-6304
    Keywords: GC ; Signal averaging ; Detection limit ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ensemble or signal averaging has been used to increase detection limits in gas chromatography. The sample is injected several times into a gas chromatograph and the chromatograms generated are summed. The resulting chromatogram is treated as a separate chromatogram with the benefit of an improved signal-to-noise ratio. Use of the technique enables reliable quantitation, the time invested being used to convert an unacceptable signal-to-noise ratio into useful data. A discussion and some applications of the technique are described.
    Additional Material: 7 Ill.
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  • 119
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 120
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 41-42 
    ISSN: 0935-6304
    Keywords: HPLC ; Ion exchange ; Volatile mobile phases ; Nucleotides ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 121
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 61-61 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 122
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 171-175 
    ISSN: 0935-6304
    Keywords: Coupled LC-GC-MS ; Loop interface ; Concurrent cosolvent evaporation ; Micro-LC ; Donor-acceptor complexes ; Fossil fuels ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A multidimensional LC-GC-MS system was developed and used to analyze complex fossil-fuel samples. The electron-acceptor stationary phase, 5 μm 2,4-dinitrophenylmercaptopropylsilica, was packed into a 0.32-mm × 350-mm microcapillary liquid chromatography (μLC) column. Aromatic fractions eluted from the μLC system at 12 μL/min and were diverted to the gas chromatograph mass spectrometer (GC-MS) by a ten-port switching valve with 50 and 7.6-μL loops. Concurrent cosolvent evaporation occurred in a 0.32-mm × 3-m precolumn ahead of a 0.25-mm × 30-m DB-5 analytical column. Solvent vapors exited through an open-split interface. The utility of the μLC-GC-MS system was demonstrated through the analyses of solvent refined coal, kerosene, and crude oil.
    Additional Material: 6 Ill.
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  • 123
    ISSN: 0935-6304
    Keywords: Enantioselective gas chromatography ; 2,3-Diacylated cyclodextrins ; Chiral flavor analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Heptakis(2,3-di-O-acetyl-6-O-tert-butyldimethylsilyl)-β-cyclo -dextrin proves to be a versatile chiral stationary phase for the direct differentiation of aroma-relevant enantiomers.
    Additional Material: 6 Ill.
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  • 124
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 180-183 
    ISSN: 0935-6304
    Keywords: GC ; Packed glass capillary column ; Gas analysis ; C1—C4 hydrocarbon analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new type of packed glass capillary column (PGCC) with a core, and its potential usage in practice are described. The permeability of the column is considerably greater than that of conventional PGCC and its N/(Pi-Po) value is also higher. This novel PGCC column has been successfully applied to the analysis of trace levels of ethyne, cyclopropane, propadiene, propyne, and other C1—C4 impurities in pure ethene, propene, 1,3-butadiene, and catalytic cracking gas samples as well as other petrochemical gases such as liquified petroleum gas.
    Additional Material: 9 Ill.
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  • 125
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 184-189 
    ISSN: 0935-6304
    Keywords: Enantioselective gas chromatography ; Cyclodextrin derivatives ; Monoterpene hydrocarbons ; Essential oils ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using a dual column gas chromatograph equipped with two capillary columns coated with heptakis(6-O-methyl-2,3-di-O-pentyl)-β-cyclodextrin (6-me-2,3-pe-β-CD) and octakis(6-O-methyl-2,3-di-O-pentyl)-γ-cyclodextrin (6-me-2,3-pe-γ-CD), respectively, all important olefinic monoterpene hydrocarbons occurring in essential oils, including α-thujene, α- and β-pinene, camphene, sabinene, α- and β-phellandrene, Δ-3-carene and limonene can be resolved into enantiomers. With the chromatographic system described the characteristic enantiomeric composition of these monoterpene hydrocarbons in essential oils can be determined.
    Additional Material: 7 Ill.
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  • 126
    ISSN: 0935-6304
    Keywords: Honey ; Free amino acids ; Capillary gas chromatography ; Heptafluorobutyryl isobutyl esters ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The chemical analysis of honey tends to concentrate on factors related to its state of preservation, e.g. HMF, diastase activity, and water content. Although there is no characteristic of honey officially regarded as suitable for certification of its botanical origin, literature is available in which several of the “minor” components of honey, such as flavors, di- and trisaccharides, and free amino acids, have been used to certify the botanical origin of the product.In this paper, six kinds of honey from different botanical sources (acacia, citrus fruit, chestnut-tree, rhododendron, rosemary, and lime-tree) were analyzed by capillary gas chromatography, and the data obtained evaluated statistically to determine whether the amino acid profile could be used to verify the botanical source of the material.The results have shown that the presence of amino acids such as arginine, tryptophan, and cystine is characteristic of a particular kind of honey, and that others, such as proline, asparagine, lysine, and methionine, can be used for discrimination if quantitative data is available about the levels of the compounds present.Evaluation of optimum split ratio for amino acid determination, and problems concerning the derivatization process, are also discussed.
    Additional Material: 3 Ill.
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  • 127
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 195-198 
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Surface ionization detection (SID) ; Midazolam ; Human plasma ; Simple extraction ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
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  • 128
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 190-194 
    ISSN: 0935-6304
    Keywords: Split injection ; Sample evaporation during injection ; Heat consumption during evaporation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: During sample evaporation in conventional vaporizing injection, the supply of heat to the evaporating liquid is a problem, first because the amounts of heat consumed are relatively large and, secondly, because the heat must be transferred to the sample within a very short time. Times available for evaporation, required amounts of heat, possible sources of heat, and the time required to transfer the heat to the sample liquid are discussed. It is shown that mixing with carrier gas contributes little heat to the evaporation process, but also that packings with glass wool have too low a heat capacity to deliver the required amount of heat to the evaporating sample. Transfer of heat from the insert wall to the sample easily requires several seconds, even if cooling of the vaporizing zone by 20° is accepted. Thus “flash evaporation” is usually impossible and most liquids must be held in the vaporizing chamber to allow full evaporation.
    Additional Material: 3 Ill.
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  • 129
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 198-200 
    ISSN: 0935-6304
    Keywords: Micellar electrokinetic capillary chromatography ; Capillary electrophoresis ; Nitroaromatics ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 130
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 201-203 
    ISSN: 0935-6304
    Keywords: Capillary zone electrophoresis ; Sample collection ; Preparative separation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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  • 131
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    Journal of High Resolution Chromatography 15 (1992), S. 207-208 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 132
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 203-205 
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; SIM-MS ; Ethyl carbamate ; Wine ; Continuous extraction ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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  • 133
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 206-206 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 134
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 209-209 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 135
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992) 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 136
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 227-234 
    ISSN: 0935-6304
    Keywords: High temperature gas chromatography ; Supercritical fluid chromatography ; Simulated distillation ; High boiling waxes ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Simulated distillation boiling range distributions have been compared for high boiling petroleum wax samples using high temperature gas chromatography and supercritical fluid chromatography. Midpoint (50 % off) temperature differences were small, and average differences between the two types of analyses were less than 6° Details of optimization of the HTGC and SFC systems and injection techniques used are reported.
    Additional Material: 11 Ill.
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  • 137
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 213-218 
    ISSN: 0935-6304
    Keywords: High resolution capillary gas chromatography (HRCGC) ; Single column capillary GC ; Isothermal and temperature programmed GC ; Analysis of multi component hydrocarbon mixtures ; One and two ring aromatic compounds ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The scope of the principal techniques employed for the analysis of hydrocarbon mixtures is discussed, with emphasis on the analysis of one and two ring aromatic compounds by single column capillary gas chromatography. The paper considers both the column and the selection of the temperature regime (isothermal and temperature programmed). Much space is devoted to the characterization of the compounds by means of retention data.
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  • 138
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    Journal of High Resolution Chromatography 15 (1992), S. 235-237 
    ISSN: 0935-6304
    Keywords: Capillary GC ; Flame photometric detection (FPD) ; Response characteristics ; Organophosphorus pesticides ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The molecular emission of heteroelements such as phosphorus and sulfur is the basis of the selective response of the flame photometric detector. The behavior of the FPD towards phosphorus compounds has been studied and design improvements sought with regard to burner configuration and temperature distribution. The possibility of differentiating between compounds containing phosphorus atoms and those containing both phosphorus and sulfur atoms has also been examined.Detection limits and response characteristics have been reported for organophosphorus pesticide residues in samples of natural origin
    Additional Material: 5 Ill.
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  • 139
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    Journal of High Resolution Chromatography 15 (1992), S. 219-226 
    ISSN: 0935-6304
    Keywords: HPLC ; Triacylglycerols (triglycerides) ; Oenothera ; Borago ; Ribes ; Primula ; Sapium ; γ-Linolenic acid (18:3 ω 6) [506-26-3] ; Estolides ; Stillingia oil ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reversed phase HPLC with short wavelength UV detection is a useful alternative to conventional separation systems, with RI detection, for the analysis of the triacylglycerols of highly unsaturated vegetable oils, including γ-linolenic acid-containing oils and technical drying oils.γ-Linolenic acid-containing triacylglycerols can be identified and separated from their α-linolenic analogs. The triacylglycerol fingerprints obtained by this technique from many γ-linolenic acid-containing oils and technical oils are highly characteristic, as is apparent from chromatograms obtained from the seed oils of Oenothera biennis, Borago officinalis, Ribes nigrum, Primula florindae, and Sapium sebiferum. Characteristic peak area ratios aid the identification of these oils, and estolide peaks are seen in Sapium seed kernel oils.The high detector response for triacylglycerols containing linoleate and/or linolenate residues may present additional advantages, e.g. in the detection of such triacylglycerols in olive oil.
    Additional Material: 5 Ill.
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  • 140
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    Journal of High Resolution Chromatography 15 (1992), S. 249-255 
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Narrow bore columns ; Separation of chlorobiphenyl congeners ; Relative retention times ; Multidimensional gas chromatography ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Retention times of fifty one important chlorobiphenyl congeners have been determined on seven narrow bore GC columns coated with different stationary phases. The retention times of the chlorobiphenyls relative to tetrachloronaphthalene were plotted for different column combinations; the plots generated can be used to choose an optimum column combination for the multidimensional gas chromatographic separation of the chlorobiphenyls.
    Additional Material: 13 Ill.
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  • 141
    ISSN: 0935-6304
    Keywords: Capillary GC ; On-line extractive alkylation ; On-line acylation ; Carboxylic acids ; Amines ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Gas chromatographic procedures are described for the determination of carboxylic acids and chlorinated anilines in water samples.Propionic acid and 2,6-difluorobenzoic acid in aqueous solution have been simultaneously alkylated and extracted by means of a continuous two-phase reaction system, and then quantitated by on-line coupled capillary gas chromatography; tetrahexyl-ammonium hydrogen sulfate was used as phase transfer catalyst and pentafluorobenzyl bromide as reagent.A factorial design approach was used to optimize on-line derivatization of aqueous propionic acid with regard to pH and concentration of phase transfer catalyst. Alkylation and extraction, under optimized conditions, followed by quantitation of the pentafluorobenzyl ester by flame ionization detection furnished a linear calibration for concentrations between 0.1 and 10 μg/ml. The relative standard deviation was 9-15 %.The continuous two-phase reaction system was also used to determine (chlorinated) anilines present in water at concentrations of 0.1-1 μg/ml; pentafluorobenzoyl chloride was used as reagent and analysis was performed by capillary gas chromatography with flame ionization or electron capture detection. The on-line acylation of p-chloroaniline was optimized with regard to pH, reagent concentration, and reaction time.The on-line reaction system worked satisfactorily for both applications, although excess reagent caused some problems with the chromatography.
    Additional Material: 6 Ill.
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  • 142
    ISSN: 0935-6304
    Keywords: Microcolumn liquid chromatography ; Enantiomeric separation ; Micellar mobile phase ; Bile acid derivatives ; 1,1′-Binaphthyl-2,2′-diyl-hydrogen phosphate ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 143
    ISSN: 0935-6304
    Keywords: Capillary GC ; Polychlorobiphenyls (PCB, ClxB) ; Polychlorodibenzodioxins (PCDD, ClxDD) ; Polychlorodibenzofurans (PCDF, ClxDF) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High resolution gas chromatography, with mass selective detection, has been used for the analysis of PCB on methyl 50 % octyl polysiloxane (SB 50 Octyl), methyl octadecyl polysiloxane, and a smectic polysiloxane (SB Smectic); and for the analysis of polychlorodibenzodioxins and polychlorodibenzofurans with 1 to 8 chlorine substituents on 100 % cyanopropyl siloxane (SP 2331), smectic polysiloxane (SB Smectic), a new polar stationary phase (DB-Dioxin). The analysis has also been performed by column coupling.
    Additional Material: 14 Ill.
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  • 144
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    Journal of High Resolution Chromatography 15 (1992), S. 277-278 
    ISSN: 0935-6304
    Keywords: Synthetic phospholipids ; Reversed phase chromatography ; Anomalous retention behavior ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 145
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    Journal of High Resolution Chromatography 15 (1992), S. 281-281 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 146
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    Journal of High Resolution Chromatography 15 (1992), S. 417-422 
    ISSN: 0935-6304
    Keywords: Ion mobility spectrometry (IMS) ; Ion mobility detection (IMD) ; Capillary GC ; Capillary SFC ; Liquid Chromatography ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ion mobility monitoring has been used for detection in gas, supercritical fluid, and liquid chromatography, illustrating its potential as a method of detection for unified chromatography. Applications presented include GC-IMD of dioxins in fly ash, SFC-IMD of vitamin E, and HPLC-IMD of alkylamines.Ion mobility spectra of several mixed supercritical fluid mobile phases are also presented. Use of methanol, acetonitrile, and dichloromethane as modifiers of supercritical carbon dioxide, and use of supercritical dichlorodifluoromethane and chlorodifluoromethane as mobile phases had little effect on the reactant ion pattern at the flow rates and concentrations used in this study. Only when acetone was used as a modifier of carbon dioxide did the positive reactant ions change significantly. No effect of modifiers or mobile phase was observed for the negative reactant ions.
    Additional Material: 8 Ill.
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  • 147
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    Journal of High Resolution Chromatography 15 (1992), S. 428-433 
    ISSN: 0935-6304
    Keywords: Capillary GC ; Serially connected capillary columns ; Wide bore open tubular columns ; Industrial solvents ; Prediction of retention times ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The gas chromatographic separation of the components of a complex mixture of industrial solvents, not possible on a single stationary phase owing to coelution of some of the compounds, has been achieved on two serially connected wide bore capillary columns of different polarity.The analysis of a mixture of twenty five compounds was optimized using the serial gas chromatography theory of Purnell and Williams. The capacity factors of sample components measured with the two columns coupled in series were found to agree with those predicted by theory, regardless of the order in which they were connected.
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  • 148
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    Journal of High Resolution Chromatography 15 (1992), S. 423-427 
    ISSN: 0935-6304
    Keywords: Optimized post-column derivatization ; Xylenol orange - cetylpyridinium bromide ; Highly sensitive detection ; Lanthanides ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rare earth elements have been separated by HPLC on octadecyl-bonded silica gel, dynamically modified with ammonium dodecylsulfate, using aqueous solutions of α-hydroxyisobutyric acid as mobile phase.The requirements and characteristics of post-column reaction with xylenol orange and cetylpyridinium bromide were investigated and optimized, and the reaction found to be highly sensitive and sufficiently rapid. The absorbance of the complex at 598 nm was not affected by the presence of α-hydroxyisobutyric acid at concentrations of the latter up to 150 mmol/l; at higher concentrations of the acid, the absorbance decreased slightly.For most of the rare earth elements the response was linear up to 0.2 mmol/l; the relative standard deviation of peak area was, typically, ∼1 %. The sensitivity of the method was usually better than 1 μg/ml.The results obtained from the determination of lanthanum, cerium, praseodymium, and neodymium in samples of apatite and bastnesite were in a good agreement with those obtained by ICP-AES.
    Additional Material: 3 Ill.
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  • 149
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    Journal of High Resolution Chromatography 15 (1992), S. 434-436 
    ISSN: 0935-6304
    Keywords: Micropacked LC ; Dry-packing method ; Column technology ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A dry-packing method has been developed which enables the preparation of packed capillary columns for micro HPLC from 250 μm i.d. tubing and 5 μm packing materials. Pressurized gases, such as hydrogen and argon, were used to transport the packing media, and ethanol or methanol were used as discharge agents. By changing the gas pressure, the packing density could be easily adjusted. It was found that, within experimental limits, the higher the packing density, the greater the column efficiency. Comparison between dry- and slurrypacked columns showed that the former had greatly improved stability; the efficiency of dry-packed columns was about the same as, or even better than, that obtained by slurry-packing.
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  • 150
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    Journal of High Resolution Chromatography 15 (1992), S. 449-451 
    ISSN: 0935-6304
    Keywords: GC ; Signal averaging ; Microbore columns ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ensemble or signal averaging, and the use of the technique for the solution of some unique problems with minimum sample handling, have previously been reported. The capability of the technique has been evaluated with microbore gas chromatography for the fast handling of a large number of analyses: ca 20-30 replicate injections are easily attainable in a reasonable analysis time. The implementation of the signal averaging technique with other concentration techniques for improving detection limits is also demonstrated.
    Additional Material: 6 Ill.
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  • 151
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    Journal of High Resolution Chromatography 15 (1992), S. 444-448 
    ISSN: 0935-6304
    Keywords: Block polysiloxanes ; Block condensation ; Chiral polysiloxanes ; Functionalized polysiloxanes ; Polycondensation ; Polysiloxane stationary phase ; Reactive polysiloxanes ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Exploitation of the full potential of selector-modified polysiloxanes as chromatographic stationary phases is limited because conventional methods of silicone synthesis involve strong acids or strong nucleophiles such as water or bases; under these conditions many potentially useful selectors decompose. The general approach to polysiloxane synthesis presented herein gives access to functionalized polysiloxanes under mild conditions. The functional groups incorporated can serve as chromatographic selectors or as electrophilic sites for secondary modification or cross-linking.
    Additional Material: 3 Ill.
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  • 152
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    Journal of High Resolution Chromatography 15 (1992), S. 437-443 
    ISSN: 0935-6304
    Keywords: Coupled LC-GC ; Polycyclic aromatic hydrocarbons ; Automation ; Clean-up and analysis ; Lubricating oil ; Urban air ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A fully automated system, comprising a liquid chromatograph (LC) coupled on-line to a gas chromatograph (GC) by means of a loop interface, has been constructed for clean-up and analysis of polycyclic aromatic hydrocarbons (PAH). An autosampler was utilized for sample injection into the LC. By the use of a back-flush technique in conjunction with an ordinary analytical aminopropylsilica column, PAH could be isolated by LC: a concurrent solvent evaporation injection technique was then used for on-line transfer of the PAH fraction to the GC, where the PAH analysis was completed.Compared with ordinary off-line LC clean-up followed by GC analysis, the sensitivity has been increased by a factor of 50-100, yielding a detection limit for individual PAH of a few nanograms per sample when using flame ionization detection. Further, irreproducible losses of low molecular weight PAH as a result of solvent evaporation steps in off-line clean-up procedures have been eliminated. Reproducibility of retention times and relative peak areas is high, facilitating automatic peak identification and calculation of concentrations, and the system can thus be used for automatic sample evaluation. The total time required for clean-up and analysis is only 1.5 hours, and the demand on personnel time for the analysis of PAH has been drastically reduced.The technique has been demonstrated with samples of urban air and of used automobile engine lubricating oil.
    Additional Material: 7 Ill.
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  • 153
    ISSN: 0935-6304
    Keywords: Capillary zone electrophoresis ; Surface modification ; Vinyl-derivatization ; Adsorption ; Polymer coating ; Polyvinylalcohol ; Proteins ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mixtures of several basic proteins have been used to test CZE capillaries with surfaces modified by new pretreatment procedures; the performance obtained has been compared with that achieved using capillaries treated by procedures described in the literature.It has been shown that addition of non-ionic polyvinylalcohols (PVA) to CZE buffer solutions deactivates even bare, i.e. untreated, fused silica surfaces and renders them suitable for separations of basic proteins. The performance obtained from such surfaces was comparable with that of capillaries modified by the more elaborate procedures of etching, silanol derivatization, and/or adsorptive coating (again with polymers).A home-made device is described which enables derivatization and coating reactions to be performed on fused silica capillaries under an inert atmosphere, i.e. one free from oxygen and water.
    Additional Material: 6 Ill.
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  • 154
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    Journal of High Resolution Chromatography 15 (1992), S. 478-479 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Kováts retention index ; GW-BASIC program ; Computer-assisted calculation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 155
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    Journal of High Resolution Chromatography 15 (1992), S. 467-471 
    ISSN: 0935-6304
    Keywords: Capillary GC ; Medium pressure liquid chromatography ; Chemiluminescence nitrogen detector ; Acetonitrile ; Propionitrile ; Naphtha ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two methods have been developed for the determination of trace levels of acetonitrile and propionitrile in light naphthas. One involves clean-up and preconcentration by medium pressure liquid chromatography (MPLC) in which nitriles are concentrated ten-fold while the complex hydrocarbon matris is removed. The concentrated solution is then analyzed by high resolution GC with flame ionization detection. The second method involves direct injection of samples into a capillary GC equipped with chemiluminescence nitrogen detection.The results and repeatability obtained from both methods are comparable. Preconcentration enables identification by GC-MS and simultaneous analysis of other polar species, with no need for selective detectors. Direct analysis is, on the other hand, much less time-consuming and requires less sample.
    Additional Material: 6 Ill.
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  • 156
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    Journal of High Resolution Chromatography 15 (1992), S. 458-466 
    ISSN: 0935-6304
    Keywords: SFC Pressure drop ; Efficiency ; Compressibility effects ; Analysis time ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The influence of the pressure drop on the efficiency and speed of analysis in packed and open tubular supercritical fluid chromatography (SFC) is described: methods previously developed to describe the effects of mobile phase compressibility on the performance of open tubular columns in SFC have been extended to packed columns.The Horvath and Lin equation has been used to elucidate the influence of variations in velocity, diffusivity, and capacity factor along the column on the overall efficiency of packed column SFC. In packed columns, in contrast with the situation in open tubular columns, because the increase in velocity is no longer compensated by an increase in diffusion coefficients, the increase in both linear velocity and capacity factor which result from a significant pressure drop cause the plate height to increase along the column.The effect of fluid decompression along the length of the column on the speed of analysis in SFC has been studied and numerical expressions derived which enable calculation of compressibility correction factors for the plate height. Both the f1 and f2 correction factors remain very close to unity for acceptable pressure drops, which means that the pressure drop has virtually no effect on the number of plates generated per unit time for an unretained component. For retained species, the decompression of the mobile phase across the column causes the capacity factor to increase and hence leads to increased analysis times.
    Additional Material: 3 Ill.
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  • 157
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    Journal of High Resolution Chromatography 15 (1992), S. 472-477 
    ISSN: 0935-6304
    Keywords: Headspace sampling techniques ; Capillary gas chromatography ; Detection techniques ; Volatile compounds ; Fresh fruit ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The composition of volatile compounds produced by fruit during growth and post-harvest storage and ripening has been studied and the different headspace methods compared. Static and dynamic headspace sampling have been compared and evaluated according to their capacity to collect and concentrate volatiles from the atmosphere surrounding the fruits, and FID, MSD, and organoleptic detection have been compared. The results emphasize that the headspace sampling procedure selected is crucial to the performance of subsequent analysis.
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  • 158
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    Journal of High Resolution Chromatography 15 (1992), S. 486-488 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 159
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    Journal of High Resolution Chromatography 15 (1992), S. 555-561 
    ISSN: 0935-6304
    Keywords: RPHPLC ; Prediction of retention time ; Quaternary mobile phase ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 6 Tab.
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  • 160
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    Journal of High Resolution Chromatography 15 (1992), S. 562-563 
    ISSN: 0935-6304
    Keywords: Reversed phase ; Variable wavelength ; Dye intermediates ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 161
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    Journal of High Resolution Chromatography 15 (1992), S. 564-565 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 162
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    Journal of High Resolution Chromatography 15 (1992) 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 163
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    Journal of High Resolution Chromatography 15 (1992), S. 569-569 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 164
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    Journal of High Resolution Chromatography 15 (1992), S. 579-584 
    ISSN: 0935-6304
    Keywords: GC Analysis ; LC Analysis ; Preparative LC purification ; Syntheses ; Alkylated cyclodextrins ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methods of alkylation of α-, β- and γ-cyclodextrins have been optimized with regard to the parameters of reaction, degree of alkylation and yields. The analysis of the reaction mixtures and of the isolated single species has been performed by high temperature GC and HPLC. The phase systems of the preferably applied HPLC have been carefully adjusted by variation of both the stationary and mobile phases to the very different hydrophobicities of the various alkylated CD species which have been synthesized. Several partially or fully alkylated CD species were isolated from preparative scale HPLC separations in high purity.
    Additional Material: 10 Ill.
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  • 165
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    Journal of High Resolution Chromatography 15 (1992), S. 573-578 
    ISSN: 0935-6304
    Keywords: Capillary zone electrophoresis ; Switchable electroosmotic flow ; Proteins ; Oligosaccharides ; Nucleotides ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A surface modification has been developed which yields fused silica capillaries with switchable electroosmotic flow (anodal/cathodal). The capillary surface is a composite material consisting of unreacted silanol groups, a layer of positively charged quaternary ammonium functions, and a hydrophilic layer of long polyether chains. Because of the presence of positively and negatively charged groups, the net charge of the capillary surface can be varied from positive to negative by changing the pH of the running electrolyte, thus enabling manipulation of the magnitude and direction of the electroosmotic flow. The long polyether chains were effective in shielding biomacromolecules from the charged inner surface of the capillary, thus minimizing electrostatic interaction of the solutes with both unreacted silanols and the quaternary ammonium groups which had been introduced. As a consequence, high separation efficiencies were achieved with proteins, nucleotides, and a series of acidic oligosaccharides.
    Additional Material: 7 Ill.
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  • 166
    ISSN: 0935-6304
    Keywords: Enantioselective GC ; 2,3-Di-O-methyl-6-O-tert-butyldimethylsilyl cyclodextrins ; Influence of bulky TBDMS group ; Solubility ; Chiral selectivity ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The characteristics of the new chiral stationary phase heptakis(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)-β-cyclodextrin are outlined and compared with permethyl- and perethyl-β-cyclodextrins.
    Additional Material: 7 Ill.
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  • 167
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    Journal of High Resolution Chromatography 15 (1992), S. 585-589 
    ISSN: 0935-6304
    Keywords: High temperature GC ; Direct chemical ionization MS (DCIMS) ; Glass capillary columns ; On-column injection ; Carbohydrates ; Sucrose fatty acid esters ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A commercially available high temperature GC system has been investigated to determine its suitability for the automated analysis of sucrose fatty acid esters. In comparison with conventional GC, the high temperature variety broadens the scope of the technique to encompass high molecular weight carbohydrate derivatives while maintaining high separation efficiency. Despite the broad range of polarities, simultaneous quantification of educts and sucrose fatty acid ester fractions is possible in one run, after derivatization. Chromatographic requirements, sample preparation, structure verification by direct chemical ionization mass spectrometry, and advantages and limitations of the high temperature GC-analysis are discussed.
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  • 168
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    Journal of High Resolution Chromatography 15 (1992), S. 594-600 
    ISSN: 0935-6304
    Keywords: On-line evaporator ; Coupled LC systems ; Evaporation by vapor overflow ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mobile phase of a fraction eluted from a first LC column is removed by an on-line evaporator in order to reconcentrate the solute material or to exchange the eluent before performing a subsequent LC separation. Evaporation essentially occurs by concurrent evaporation, i.e. the solvent evaporates at a rate equal to the flow rate of the incoming eluent, and is driven by the overflow principle, i.e. vapors leave the tube as a result of the expansion resulting from evaporation.The liquid is introduced into a small tube (e.g., 4 cm × 1.3 mm i.d.) which is packed, e.g., with a coarse silica gel. The outlet of the evaporator is connected to vacuum in order to enable evaporation at reduced temperature and to increase retention of the volatile components. With normal phase eluents, evaporation rates may approach 1 ml/min; n-dodecane was the most volatile n-alkane fully retained by the evaporator.
    Additional Material: 7 Ill.
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  • 169
    ISSN: 0935-6304
    Keywords: Capillary GC ; Mass selective detection ; Chronic renal failure ; Hemodialysis ; Hemofiltration ; Peritoneal dialysis ; Furanpropionic acid ; Hippuric acid ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Solid-phase extraction, capillary GC, and mass selective detection have been used to determine 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid (furanpropionic acid) and hippuric acid in the plasma of patients with chronic renal failure. The concentrations of furanpropionic acid and hippuric acid were found to be highly elevated and reached levels of 4.56 ± 2.37 mg/dl (10 to 20-fold higher than normal) and 12.90 ± 14.06 mg/dl (40 to 60-fold), respectively. Treatment by hemodialysis and hemofiltration effectively eliminated hippuric acid (on average by 66 and 56%, respectively) but had little effect on furanpropionic acid. Intermittent peritoneal dialysis gave the best long-term results. Both components were maintained at a lower level than by hemodialysis and hemofiltration.
    Additional Material: 4 Ill.
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  • 170
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    Journal of High Resolution Chromatography 15 (1992), S. 609-612 
    ISSN: 0935-6304
    Keywords: Capillary GC ; Quality control ; Diesel fuel substitute ; Vegetable oil methyl esters ; Mono-, di-, and triglycerides ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Vegetable oil methyl esters are increasingly being used as substitutes for petroleum-based diesel fuels. Because the presence of triglycerides and partial glycerides in the fuel as a result of incomplete transesterification of vegetable oils can lead to serious engine problems, continuous quality control of the product is essential. A rapid gas chromatographic method has been developed for the quantitative determination of mono-, di-, and triglycerides in vegetable oil methyl esters.Prior to analysis, mono-, and diglycerides were silylated with N,O-bis(trimethylsilyl)trifluoroacetamide; tridecanoin was used as internal standard. Calibration was performed by analysis of standard solutions containing mono-, di-, and triolein: the calibration plots for mono- and diglycerides showed good linearity, whereas for triglycerides no linearity was observed for triolein concentrations below 0.05 mg/ml. When a non-linear multi level calibration was employed for the quantitation of triglycerides, the method gave excellent quantitative results for mono-, di-, and triglycerides in vegetable oil methyl esters.
    Additional Material: 2 Ill.
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  • 171
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    Journal of High Resolution Chromatography 15 (1992), S. 613-614 
    ISSN: 0935-6304
    Keywords: Press fit connections ; High temperature fused silica ; Polyimide ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Recently introduced fused silica, primarily of the high temperature type, no longer allows the formation of a reliable press-fit seal. Attempts to tighten the connection with various kinds of glue proved unsatisfactory. Manufacturers of fused silica tubing are urged to devote more attention to the problem.
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  • 172
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    Journal of High Resolution Chromatography 15 (1992), S. 620-621 
    ISSN: 0935-6304
    Keywords: Reversed phase LC ; Precolumn derivatization ; Hydrazine analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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  • 173
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    Journal of High Resolution Chromatography 15 (1992), S. 615-619 
    ISSN: 0935-6304
    Keywords: Capillary GC ; Splitless injection ; Electronic pressure control (EPC) ; Nitrogen - phosphorus detector (NPD) ; Flame photometric detector (FPD) ; Flame ionization detector (FID) ; Programmable cool on-column injection ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: HP 5890 Series II Gas Chromatographs are equipped with prototype hardware enabling electronic pressure programming of all detector and carrier gases. A method of using electronic pressure control (EPC) to optimize detector performance (sensitivity, selectivity, and baseline stability) is demonstrated. With EPC, sample introduction, column separation, and detector performance can be optimized simultaneously without the classical trade-offs in performance. An example is also presented of the use of a new automated system which enables cool on-column injection into 250 or 320 μm columns without the need for a retention gap.
    Additional Material: 6 Ill.
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  • 174
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    Journal of High Resolution Chromatography 15 (1992), S. 622-625 
    ISSN: 0935-6304
    Keywords: HPLC ; Spectrophotometric detection ; Electrochemical detection with 8-quinolinol ; Metal complexes ; Serum ; Copper ; Iron ; Aluminum ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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  • 175
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    Journal of High Resolution Chromatography 15 (1992), S. 627-628 
    ISSN: 0935-6304
    Keywords: LC-MS ; Magic LC-MS interface ; Soot ; Fullerenes ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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  • 176
    ISSN: 0935-6304
    Keywords: Capillary affinity gel electrophoresis ; Poly(9-vinyladenine) ; Gene analysis ; Separation of oligonucleotides ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 177
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    Journal of High Resolution Chromatography 15 (1992), S. 629-631 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 178
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    Journal of High Resolution Chromatography 15 (1992), S. 631-631 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 179
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    Journal of High Resolution Chromatography 15 (1992), S. 632-632 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 180
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    Journal of High Resolution Chromatography 15 (1992) 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 181
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    Journal of High Resolution Chromatography 15 (1992), S. 633-633 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 182
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    Journal of High Resolution Chromatography 15 (1992), S. 637-640 
    ISSN: 0935-6304
    Keywords: Capillary GC ; On-column injection ; Plasma samples ; Retinoid analysis ; Acitretin isomers ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The capillary gas chromatographic (CGC) analysis of the der-matological drug trans-acitretin (NeotigasonR) and its cis metabolite is described. Separation of the methyl ester derivatives can be achieved on a 90% biscyanopropylsiloxane phase. The importance of using cold on-column injection and short, thin film capillary columns is discussed. For patients treated with the prodrug of acitretin, etretinate (TigasonR), i.e. the ethyl ester of Neotigason, three compounds have to be separated. Selectivity tuning is required for successful CGC separation. An alternative can be found in the selectivity of ion monitoring mass spectroscopy. Analysis of plasma samples involves liquid-liquid extraction, a derivatization step, and HPLC purification.
    Additional Material: 5 Ill.
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  • 183
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    Journal of High Resolution Chromatography 15 (1992), S. 641-654 
    ISSN: 0935-6304
    Keywords: GC-MS ; LC-MS ; Garlic ; Licorice ; Anticarcinogen ; Isoflavanoid ; Triterpenoid ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nine organosulfur compounds present in an aged garlic extract and two isoflavonoids and one triterpenoid present in a licorice root extract powder have been identified and quantified. Quantification involved solvent extraction and gas chromatographic - mass spectrometric analysis (garlic extract) or hydrolysis, solvent extraction, and liquid chromatographic analysis (licorice root extract powder).Although the garlic extract proved to be unstable and the concentration of the organosulfur compounds varied with time, one analysis of the extract gave the following results: methyl disulfide (0.607 μg/g), methyl trisulfide (0.181 μg/g), allyl sulfide (2.02 μg/g), allyl disulfide (0.784 μg/g), allyl trisulfide (0.795 μg/g), allyl methyl sulfide (1.64 μg/g), allyl methyl disulfide (0.411 μg/g), allyl methyl trisulfide (0.695 μg/g), and ethyl 2-propenesulfinate (11.4 μg/g). The analysis of the licorice root extract powder gave the following results: formononetin (1.92 mg/g), isoliquiritigenin (9.61 mg/g), and 18β-glycyrrhetinic acid (43.9 mg/g).Methods were successfully developed to quantify the same compounds in the serum of test animals which had consumed feed spiked with garlic extract or licorice root extract powder. Only the 18β-glycyrrhetinic acid could be detected in the sera of such animals, however. An effort was also made to determine serum levels of prostaglandin E2 to correlate its inhibition with levels of the dietary components, but the prostaglandin E2 levels were too low to measure.
    Additional Material: 14 Ill.
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  • 184
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    Journal of High Resolution Chromatography 15 (1992), S. 665-668 
    ISSN: 0935-6304
    Keywords: Capillary GC ; Inductively coupled plasma MS ; Element-selective detection ; Organotin speciation ; Organometallic compounds ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The separation and detection of volatile organometallic compounds containing tin, iron, and nickel has been achieved using capillary GC-inductively coupled plasma-mass spectrometry (capillary GC-ICP-MS). Detection limits range from 3.0 to 7.0 pg/s. The presence of volatile organotin compounds in a harbor sediment has been confirmed. The retention range of the organometallic compounds analyzed by capillary GC-ICP-MS has been extended considerably beyond that possible in earlier studies (retention indices up to 3400).
    Additional Material: 5 Ill.
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  • 185
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    Journal of High Resolution Chromatography 15 (1992), S. 659-664 
    ISSN: 0935-6304
    Keywords: Splitless injection, 100 μl volumes ; Injector insert, packing of ; Sample evaporation in vaporizing injector ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: If a sample evaporates by flash vaporization in an empty injector insert, the solute material is well mixed with the expanding solvent vapors and the maximum injection volume is determined by the requirement that no vapors must leave the vaporizing chamber. If evaporation occurs from a surface (e.g., of Tenax packing), however, the solvent evaporates first. The site of evaporation is cooled to the solvent's boiling point, and the cool island formed in the hot injector retains solutes of at least intermediate boiling point (visually observed for perylene). Solvent vapors, free from such solutes, may now expand backwards from the injector insert and leave through the septum purge exit. When solvent evaporation is complete, the site of evaporation warms up, causing the high boiling solutes to evaporate and to be carried into the column by the carrier gas. The technique somewhat resembles PTV injection, but is performed using a classical vaporizing injector.
    Additional Material: 6 Ill.
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  • 186
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    Journal of High Resolution Chromatography 15 (1992), S. 655-658 
    ISSN: 0935-6304
    Keywords: Capillary GC ; Derivatized cyclodextrins ; Enantiomer separation ; Chromatographic performance ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper reports the chromatographic performance of columns coated with 2,3,6-trimethyl-α-, β-, and γ-cyclodextrins (2,3,6-TriMe-α,- β-, and γ-CD) and their derivatives 2,6-dimethyl-3-trifluoroacetyl-α-, β-, and γ-cyclodextrins (2,6-DiMe-3-TFA-α-, β-, and γ-CD), all six diluted in polysiloxane, for the separation of the enantiomers of volatile compounds.The influence of column length and film thickness on separation is reported. Phenomena related to reproducibility and consistency, over a period of time, of columns prepared with these CD derivatives are also discussed, and a possible solution to some drawbacks reported here is proposed.
    Additional Material: 3 Ill.
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  • 187
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    Journal of High Resolution Chromatography 15 (1992), S. 677-681 
    ISSN: 0935-6304
    Keywords: Capillary GC ; Atomic emission spectroscopy ; Radio frequency plasma ; Oxygen-selective detection ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A radio frequency plasma detector for capillary GC has been modified for oxygen-selective detection. Purification of the plasma gas and purging of both ends of the discharge region with helium were crucial to minimizing oxygen background emission from impurities in the plasma. With a pure helium plasma, eluting hydrocarbons released oxygen from the discharge region resulting in interfering signals on the oxygen channel. These interfering signals were efficiently reduced by using a methane-doped (0. 15%) low power RF plasma (15 W) sustained in a high make-up flow (150 mL/min). With this plasma, a 103:1 oxygen-to-carbon selectivity and a 100 pg oxygen/s detection limit were obtained. The detector was linear over three orders of magnitude. The detection system has been used to screen for oxygenated compounds in two environmental samples.
    Additional Material: 6 Ill.
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  • 188
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    Journal of High Resolution Chromatography 15 (1992), S. 682-685 
    ISSN: 0935-6304
    Keywords: HPLC ; Polycyclic aromatic sulfur heterocycles (PASH) ; Sulfone method ; Diesel fuel ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An oxidation method (sulfone method) for the determination of polycyclic aromatic sulfur heterocycles (PASH) in diesel fuel is presented. The aromatic fraction of a diesel fuel, isolated by solid phase extraction, is oxidized under controlled conditions with hydrogen peroxide. The oxidation products, mainly methylated dibenzosulfone, are determined and quantified directly, without further clean-up, by HPLC with photodiode-array detection.
    Additional Material: 5 Ill.
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  • 189
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    Journal of High Resolution Chromatography 15 (1992), S. 694-695 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 190
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    Journal of High Resolution Chromatography 15 (1992), S. 669-676 
    ISSN: 0935-6304
    Keywords: Selective GC detection of metals ; Atomic emission detection ; Microwave-induced plasma ; Metal-containing compounds ; Metalloporphyrins ; Organomanganese ; Organotitanium ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Element-selective GC detection by microwave-induced plasma atomic emission spectroscopy has been used to examine a wide variety of compounds containing metals, non-metals, and metalloids. “Recipes”, or new selective detection schemes for use with the software of the computer-controlled system, have been developed for the selective detection of boron, aluminum, gallium, titanium, vanadium, chromium, manganese, rhenium, palladium, and platinum. Figures of merit including limits of detection, linear dynamic range, and spectral selectivity over carbon have been established for most of these elements. Gas chromatography - atomic emission detection (GC-AED) has been applied to the selective detection of vanadium, nickel, and iron in metalloporphyrins present in crude oil, manganese-selective detection of methylcyclopentadienylmanganese tricarbonyl (MMT) in gasoline, and titanium-selective detection of reaction mixtures containing titanium catalysts or titanium boride molecular precursors.
    Additional Material: 10 Ill.
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  • 191
    ISSN: 0935-6304
    Keywords: Pyrolysis-capillary GC ; Quantitative analysis ; Detection limit ; Ultra-thin layer poly(methyl methacrylate) ; Poly(ethylene terephthalate) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The determination of nanometer thick layers of poly(methyl methacrylate) coated on to the surface of poly(ethylene terephthalate) film has been investigated by high resolution pyrolysis gas chromatography without sample pretreatment or modification of the instrumentation used. A good linear relationship was observed between the quantity of the characteristic pyrolysate and the thickness of the poly(methyl methacrylate) layer; the detection limit was sufficient to enable the quantitation of poly(methyl methacrylate)-to-poly(ethylene terephthalate) film thickness ratios of 1:20000 in composite materials.
    Additional Material: 2 Ill.
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  • 192
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    Journal of High Resolution Chromatography 15 (1992), S. 18-23 
    ISSN: 0935-6304
    Keywords: Compound identification ; Multicomponent separation ; Retention calculation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A procedure for the identification and separation of unknown compounds by capillary gas chromatography is described. The procedure involves a live retention time database and optimization of the separation. After initial chromatography of the sample, a rough search lists all the possible compounds it might contain and the analyst then uses his experience to discard those compounds in the list which are unlikely to be present. The multi-component separation is then optimized over the whole range of defined starting temperatures and programming rates, in order to produce the best possible separation of the sample components, and the chromatography repeated using the results obtained from the optimization procedure. Further search operations within a given search window will then report the compound names, and related information, for each peak.Since the identification operation is performed at least twice during the procedure, and the optimization of the separation assists the identification by separating possibly overlapped peaks, the confidence of the qualitative analysis is higher than may be obtained using standards alone. If the reproducibility of isothermal indices measured on columns could be guaranteed, this procedure could be used instead of performing chromatography on standards of the compounds contained in the database, regardless of changes in column dimensions, phase ratio, and operating conditions in temperature programmed analysis.
    Additional Material: 4 Ill.
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  • 193
    ISSN: 0935-6304
    Keywords: Electrolytic conductivity detection ; Nitrogen-mode optimization ; Open tubular columns ; Food contaminants ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The combination of open tubular column gas chromatography with electrolytic conductivity detection has been evaluated for the determination of nitrogen-containing pesticide residues in food extracts. Optimization of the column position at the column-detector interface was crucial to the successful operation of the detector. The signal-to-noise ratio and response stability of the detector are greatly influenced by the composition of the electrolyte solvent. Large volume splitless injections using retention gaps and optimized detector operating conditions enabled pesticide residues in food extracts to be determined at sub parts-per-million levels. Although the electrolytic conductivity detector is less sensitive than the thermionic ionization detector, its greater nitrogen selectivity can he crucial to the determination of nitrogen-containing contaminants in food extracts, particularly in complex mixtures where phosphorus-containing contaminants or matrix compounds are also present.
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  • 194
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    Journal of High Resolution Chromatography 15 (1992), S. 140-142 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 195
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    Journal of High Resolution Chromatography 15 (1992), S. 136-139 
    ISSN: 0935-6304
    Keywords: HPLC ; MECC ; Plant extracts ; Flavonol aglycones ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 7 Ill.
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  • 196
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    Journal of High Resolution Chromatography 15 (1992), S. 136-136 
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Press fit connectors and splitters ; Re-use ; Cleaning ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 197
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    Journal of High Resolution Chromatography 15 (1992), S. 49-51 
    ISSN: 0935-6304
    Keywords: Micro HPLC ; Methotrexate ; Clinical analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 198
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    Journal of High Resolution Chromatography 15 (1992), S. 46-48 
    ISSN: 0935-6304
    Keywords: GC-MS ; Electron impact (EI) ; Thermal degradation ; Propoxyphene ; Benzoylecgonine ; Atropine ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
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  • 199
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    Journal of High Resolution Chromatography 15 (1992), S. 43-45 
    ISSN: 0935-6304
    Keywords: Elution order ; Structure and elution order ; Thiocarbamates ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
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  • 200
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    Journal of High Resolution Chromatography 15 (1992), S. 51-54 
    ISSN: 0935-6304
    Keywords: Capillary GC ; Capillary column sampling ; Aqueous samples ; PAHs ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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