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.