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W Giger

Publications and source records attributed to W Giger.

4 recordsLinked to original sources
PubMed1992

Quantitative determination of sulfonated aliphatic and aromatic surfactants in sewage sludge by ion-pair/supercritical fluid extraction and derivatization gas chromatography/mass spectrometry.

Secondary alkanesulfonate (SAS) and linear alkylbenzene-sulfonate (LAS) surfactants were quantitatively (> 90%) extracted from sewage sludges as their tetrabutylammonium ion pairs using 400 atm of supercritical CO2 for 5 min of static extraction followed by 10 min of dynamic extraction at 80 degrees C. Ion pairs of SAS and LAS quantitatively formed butyl esters in the injection port of the gas chromatograph and were determined by gas chromatography/mass spectrometry without class fractionation of the sewage sludge extracts. Concentrations of SAS and LAS in sludges from five different sewage treatment plants ranged from 0.27 to 0.80 g/kg of dry sewage sluge and from 3.83 to 7.51 g/kg, respectively. Good reproducibility was achieved with RSDs of typically 5% for replicate extractions and analyses. Homologue and isomer distributions of SAS in sewage sludge indicated an enrichment of the more hydrophobic components in sewage sludge during sewage treatment.

Alkanesulfonates↗
PubMed1978

Bile acid pattern in human amniotic fluid.

Individual bile acids were determined in twenty-nine amniotic fluid specimens obtained from twenty-six women between the 32nd and 41st week of gestation. Total bile acid concentration ranged from 0.4 to 4.8 mumol/l with a mean of 1.57 mumol/l. Besides the two major bile acids of man, cholic acid and chenodeoxycholic acid, 3beta-hydroxy-5-cholenoic acid was found in all, lithocholic acid in ten and deoxycholic acid in nine of the twenty-nine amniotic fluid samples. 3beta-Hydroxy-5-cholenoic acid averaged 39.8% of total bile acids during 32-37 weeks of gestation and 20.2% at term (P less than 0.01). These findings point towards important differences between fetal and adult bile metabolism and may reflect maturation of hepatic bile acid biosynthesis near term.

Amniotic Fluid↗
PubMed1977

[Detection of 3 beta-hydroxy-5-cholenoic acid in human amniotic fluid].

Studies of the bile acids of human meconium suggest that a fetal pathway of bile acid synthesis exists which leads to formation of 3beta-hydroxy-5-cholenoic acid, a bile acid not found in serum of healthy pregnant women. To obtain additional support for this hypothesis, cholic, chenodeoxycholic, and 3beta-hydroxy-5-cholenoic acid were measured in amniotic fluid specimens from 18 pregnant women without liver disease. The finding of a considerable percentage of 3beta-hydroxy-5-cholenoic acid (mean: 34 molar %; range 3-71 molar % of total bile acids) in amniotic fluid strengthens the hypothesis that a fetal pathway of bile acid synthesis exists which begins with oxidation of the cholesterol side chain.

Adolescent↗