DETERMINATION OF SULFUR IN BIOLOGICALLY IMPORTANT SUBSTANCES BY PYROLYSIS-GAS CHROMATOGRAPHY

An analytical method for the determination of sulfur in biologically important substances has been developed using pyrolysis-gas chromatography (Py-GC) equipped with a flame photometric detector (FPD). This method is based on the determination of dimethyl sulfide (CH3SCH3) and hydrogen sulfide (H2S), each of which is one of the pyrolysis products of the sulfur compounds contained in protein. The protein sample was pyrolyzed instantaneously at high temperature (590 degrees C) in a stream of nitrogen gas. The Py-GC method developed in the present study does not require any pretreatment and the analysis time for determining sulfur in biological samples is as quick as 30 min. The sulfur detection limit of this method was 40 ng for methionine and 60 ng for cystine and cysteine. The coefficient of variation was 5.7, 11 and 14% for methionine, cystine and cysteine, respectively. The determination of sulfur in biologically important substances such as human hair, dog hair, silk, etc, was carried out by the proposed Py-GC method, The analytical results revealed that sulfur is 3.3-4.3 wt.% in human hair and 2.4-3.5 wt.% in dog hair.