Hydrogen sulphide and total acid-volatile sulphide in faeces, determined with a direct spectrophotometric method.

Hydrogen sulphide may be important in human bowel pathophysiology. Available methods for determination of hydrogen sulphide and total sulphide have not been validated for faeces. This paper reports on a method for direct determination of sulphide in faecal homogenates, and techniques for collecting faeces to permit determination of both hydrogen sulphide and total sulphide. Mean total sulphide and mean hydrogen sulphide concentrations were 0.66 and 0.17 mumol/g wet faeces, respectively. These concentrations are much higher than previous estimates. There was no significant difference between methanogenic and non-methanogenic faeces. Significant sulphidogenesis occurred in both methanogenic and non-methanogenic in vitro faecal incubations, with both sulphate and cysteine sources. These results do not support previous claims that sulphidogenesis occurs only in non-methanogenic faeces.