New methods for the release of volatile sulfur compounds from human serum: its determination by Tenax trapping and gas chromatography and its application in liver diseases.

New methods are described for the release of sulfur volatiles from human serum or whole blood and for its determination by Tenax trapping and gas chromatography by use of a specific sulfur detector. Methanethiol (MT) is covalently bound in serum in at least two different ways. One fraction of MT is released by addition of acid and is covalently bound to a compound with a mol wt less than 500, probably as methyl-beta-D-thioglucuronide. Another fraction of MT is released by reaction with dithiothreitol and is covalently bound to proteins in a disulfide linkage. No significant differences were observed in the protein-bound MT fraction between normal individuals and patients with cirrhosis. In contrast, the acid-hydrolyzable MT fraction was significantly elevated (P less than 0.0001) in the group with cirrhosis (0.41 +/- 0.19 mumol/L, mean +/- SD, n = 39) compared with the normal group (0.22 +/- 0.04 mumol/L, n = 21). The acid-hydrolyzable MT fraction is excreted in the urine. The concentration in normal persons amounted to 9 to 37 mumol/L. Dimethylsulfide (DMS) was measured in whole blood. There was a close correlation between venous blood DMS concentration and its concentration in breath. Dimethyldisulfide was not present in detectable amounts in the blood of normal individuals. Ethanethiol was absent in the serum and blood of all studied subjects.