ISSN:0935-6304    

DOI:10.1002/jhrc.1240140902

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractA procedure is described for the quantitative determination of amino acids in hepatic and brain tissue samples from the rat. Because the presence of certain matrix components in the tissue material led to interference with chromatographic analysis they were removed by a prechromatographic “clean‐up” step.Quantitative analysis of amino acids, as theirN‐heptafluorobutyryliso‐butyl ester derivatives, was achieved by high resolution gas chromatography on an apolar fused silica open tubular column. Reproducibility data from the complete procedure are presented; coefficients of variation for arginine and histidine in hepatic tissue varied between 7.1 and 10.1% whereas those for most other amino acids were better than 5%, with a mean recove

ISSN:0935-6304    

DOI:10.1002/jhrc.1240140903

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe identification of beer bitter acids in a pre‐isomerized hop extract by means of their UV‐spectra is described. Preliminary data for the analysis of these compounds in beer samples are presen

ISSN:0935-6304    

DOI:10.1002/jhrc.1240140904

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractStatic headspace analysis by gas chromatography has been found to be a suitable method for the analysis of organic solvents in printing inks. Experimental conditions for the analysis have been optimized, and the accuracy and relative standard deviation of the method has been determined. The solvent content of 29 printing inks has been measured.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240140905

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractInternal calibration in modified hydrodynamic chromatography has been realized by the approach ofPrieveandHoysan,i.e.the use of polystyrene monodisperse latexes to evaluate the equivalent capillary radius,R. The value obtained has been used to estimate the average sizes of a variety of liposome samples from egg yolk lecithin.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240140906

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractChlorobiphenyl congeners (CBs) are used as indicator compounds in analysis performed to determine whether or not PCB concentrations in food products, waste mineral oil, and environmental samples comply with the maximum levels permitted by legislation. Seven of these compounds have been checked for coelution with other CB congeners by means of a multidimensional gas chromatographic method utilizing a combination of two narrow bore columns, one coated with a conventional non‐polar stationary phase and the other with a liquid crystalline (smectic) stationary phase.Peaks of the relevant CBs have been transferred, by heart cutting, from the non‐polar column to the liquid crystal column, on which unambiguous separation from possible coeluting CB congeners was obtained. It has been shown that if the seven congeners are analyzed solely on a single, non‐polar capillary column the results obtained for two of them may be affected by coelution of other comp

ISSN:0935-6304    

DOI:10.1002/jhrc.1240140907

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe determination of organochlorine pesticides and polychlorinated biphenyls in milks requires the use of efficient extraction methods. A rapid procedure has been developed, based on extraction of organochlorine residues from milk on to octadecylsilica solid phase extraction cartridges and elution with hexane. The addition of different organic solvents to the milk before solid phase extraction has been studied. The use of methanol to disrupt the fat globules enables almost complete recovery of the residues with minimum extraction of fatty substances.Recovery experiments were performed for eighteen compounds present at ppb levels in whole, two per cent, and skimmed milks. The average recoveries of the compounds from two per cent and skimmed milks were 73–84%; values for whole milk were lower. The residues were determined by gas chromatography using two kinds of capillary column (non‐polar and semi‐polar) and electron capture detection. The procedure shows low lipid carry over, and extraneous interferences are minimal.The method has been applied to the detection of organochlorine pesticides and nine individual polychlorinated biphenyls in commercial milks. The results obtained demonstrated the presence of very low levels of organochlorine residues in the commercial milks ana

ISSN:0935-6304    

DOI:10.1002/jhrc.1240140908

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThirty five nitroaromatic compounds (currently listed in EPA Method 8091) and 1,4‐naphthoquinone have been separated on DB‐5–DB‐1701 and SPB‐5–SPB‐1701 column pairs, which were in each case connected to an inlet splitter and separate electron capture detectors. Retention times are included for 21 additional compounds evaluated for their suitability as internal standards and/or surrogate compounds for incorporation into Method 8091. Method reproducibility and linearity are discussed, and results are presented for extracts of two real samples spiked with the 35 nitroaromatic compounds and 1,4‐naphthoquinone and analyzed using the dual‐column‐dual

ISSN:0935-6304    

DOI:10.1002/jhrc.1240140909

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractA helium alternating current plasma detector in combination with HPLC has been evaluated for the determination of arsenic and selenium‐containing compounds after post‐column hydride generation. The construction, operation, and optimization of the system is presented. Detection limits for the compounds under study ranged from 45–60 pg/s. Determination of arsenic and selenium in spiked river water samples has been used to demonstrate the applicability of the tech

ISSN:0935-6304    

DOI:10.1002/jhrc.1240140910

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe programmable temperature vaporizing injector (PTV) has been used to study the effects of injection temperature and initial heating period on the FID response factors of TBDMS derivatives of 17 protein amino acids. The relative response factors were calculated for injection temperatures of 50°C, 90°C, 160°C, 220°C, and 260°C with different initial heating periods (1 s, 5 s, and 10 s) and the results compared with the values obtained for the calculated response factors obtained under classical split injection conditions (300°C, continuous). Except for expected peak broadening effects, the initial heating period does not seem to have significative effects on relative peak areas. The response to the derivatives of alanine, glycine, α‐aminobutyric acid, valine, proline, methionine, cysteine, phenylalanine, asparagine, and arginine was only slightly affected by increasing the injection temperature whereas the response factors for the derivatives of serine, threonine, glutamic acid, lysine, histidine, tyrosine, and tryptophan were strongly dependent upon initial injection temperatures, decreasing rapidly at temperatures above 160°C. The cold split‐splitless injection is clearly advantageous over the classical hot injection techniques for the analysis of this type of aminoacid

ISSN:0935-6304    

DOI:10.1002/jhrc.1240140911

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY