Simultaneous assay of pentachlorophenol and its metabolite, tetrachlorohydroquinone, by gas chromatography without...

A sensitive capillary gas chromatographic method was developed for the simultaneous determination of pentachlorophenol and its major metabolite, tetrachlorohydroquinone, in plasma, urine and feces. The method involved a simple one-step liquid-liquid extraction with diethyl ether and electron-capture detection gas chromatography on a fused-silica capillary column coated with 50% methylsilicone-50% trifluoropropylsilicone. The detection limit of both compounds was 50 ng/ml in plasma (from an initial volume of 0.1 ml), 100 ng/ml in urine and 100 ng/g in feces. Optimal conditions for both chemical and enzymatic hydrolysis were defined to measure conjugates of both pentachlorophenol and tetrachlorohydroquinone in urine. Tetrachlorohydroquinone was found to be unstable in plasma and urine; means to prevent its degradation during sample collection and storage by addition of ascorbic acid and ethylenediaminetetracetic acid are presented. This chromatographic method was shown to be precise, accurate and specific. It was successfully applied to toxicokinetic studies in rat.