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Detection and identification of S-methylcysteine in urine of workers exposed to methyl chloride (1980)

Doorn, R. ; Borm, P. J. A. ; Leijdekkers, Ch. -M. ; [et al.]

Springer

International archives of occupational and environmental health 46 (1980), S. 99-109

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ISSN: 1432-1246

Keywords: Methyl chloride ; Glutathione conjugation ; Thioethers ; Methylthio compounds ; Mercapturic acid ; S-methylcysteine

Source: Springer Online Journal Archives 1860-2000

Topics: Medicine

Notes: Summary Methyl chloride is used as a methylating agent and as a blowing agent in industrial processes. Alkylating agents and other electrophilic compounds are often detoxified in the organism through conjugation with glutathione. Glutathione conjugates are generally excreted as mercapturic acids, cysteine conjugates, or other thioethers in urine. Urine samples obtained from persons occupationally exposed to methyl chloride were examined for the presence of elevated thioether levels using a previously published non-selective procedure. No significant increases were detectable. A new assay procedure was developed for the detection of methylthio compounds in urine. The method is based on alkaline hydrolysis of urine samples and subsequent gas chromatographic determination of methyl mercaptan in the headspace of acidified hydrolysates. By application of this method a greatly increased excretion of a methylthio compound in the urine of CH3Cl-exposed workers was shown. The compound was identified as S-methylcysteine. A study of the urinary S-methylcysteine excretion in a group of workers during a seven-day shift revealed that two of six workers hardly excreted any S-methylcysteine after exposure to methyl chloride.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00378189

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Acidity Constants of the Thienyl- and Phenyl-Pyridines and Stability Constants of the Corresponding Copper (II) 1:1 Complexes (1972)

Sigel, Helmut ; Wynberg, Hans ; van Bergen, T. J. ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 55 (1972), S. 610-613

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The acidity constants of the six thienyl- and the three phenyl-pyridines, and the stability constants of the corresponding Cu2+ 1:1 complexes were determined in aqueous solution (I = 0.1, NaCIO4; 25°). The basicity of the pyridyl group is increased by a shift of a thienyl or phenyl group in the order 2 〈 3 〈 4 and the influence of the 2′-thienyl group is greater than that of the 3′-thienyl group. The stability of the Cu2+ 1:1 complexes formed with 3- and 4-substituted pyridines is only dependent on their basicity, as is commonly observed for structurally related ligands and their complexes. Due to steric hindrance the complexes of the 2-substituted derivatives are less stable by about 1.5 log units. There is no evidence that the aromatic bonded sulfur of 2-(2′-thienyl)-pyridine participates in complex formation with Cu2+, in opposition to an earlier claim [1].