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Biomedical subjects

W Schoknecht

Publications and source records attributed to W Schoknecht.

5 recordsLinked to original sources
PubMed1985

Stereometabolism of styrene in man: gas chromatographic determination of phenylethyleneglycol enantiomers and phenylethanol isomers in the urine of occupationally-exposed persons.

A gas chromatographic procedure for the determination of phenylethyleneglycol enantiomers and phenylethanol isomers is described and applied to the investigation of urine samples from occupationally styrene-exposed workers (11 males, six females) and an unexposed control group. Phenylethyleneglycol enantiomers and 2-phenylethanol were present in the urine samples of exposed and unexposed individuals whereas 1-DL-phenylethanol was not found in control urine. The L/D enantiomer ratio of phenylethyleneglycol was found to be approximately 3 in the exposed group and 1.5 in the control group. Because of the close structural relation of these metabolites to the primarily formed epoxide, the results give further insight into the stereotoxicity of styrene in man.

Animals↗
PubMed1984

Styrene metabolism in man: gas chromatographic separation of mandelic acid enantiomers in the urine of exposed persons.

D- and L-mandelic acid are separated by gas chromatography as isopropyl ester or isopropyl ester-isopropyl urethane on capillary columns, coated with Chirasil -Val. For its determination in urine the isopropyl ester procedure gives better results because other components of the urine do not cause interference. Thus D- and L-mandelic acid in the urine of exposed workers could be detected and verified by means of GC/MS. Occupational styrene exposure near the MAK-value (100 ppm) results in a L/D-enantiomer-ratio in urine of nearly 1.5.

Chromatography, Gas↗
PubMed1983

The determination of amino-acid enantiomers in human saliva with Chirasil-Val.

The use of polysiloxanes as stationary phase in glass-capillary gas-chromatography carrying chiral groups enables the separation and quantitation of most amino-acid enantiomers and a variety of other compounds in a much shorter time than previously. This phase exhibits low volatility and high thermal stability and may be used in routine analysis with open tubular columns at temperatures of at least 175 degrees C. Most protein amino acids are separated in a temperature programme between 90 and 175 degrees C, thus obviating the need for multiple injections. Resolution factors are lower than those of other diamide phases containing the L-valine-t. butyl-amide group, but are sufficient for resolution of almost all protein amino-acid enantiomers. Incomplete recovery from the sample, incomplete derivatization, hydrolysis and thermal decomposition of the derivative and shifting response factors can be compensated for by adding the unnatural enantiomer. The accuracy of amino-acid analysis by enantiomer labelling is equal or superior to that of known methods and permits complete analysis of peptides with respect to both amino-acid composition and the optical purity of each amino acid. The application of this method to human saliva provided information concerning enzymic and bacterial process in the mouth.

Adult↗