Determination of polysulphides in blood by gas chromatography and gas chromatography-mass spectrometry

A sensitive and simple method to determine polysulphides in human blood, using an extractive alkylation technique and gas chromatography, has been devised. Polysulphides were alkylated with pentafluorobenzyl bromide, and then converted into bis(pentafluorobenzyl)disulphide by desulphuration with potassium cyanide. The disulphide was analysed qualitatively by mass fragmentography and quantitatively by gas chromatography with electron-capture detection. The lower limit of detection was 0.005 mumol/ml. Field testing in a suicide case confirmed the validity of the method.