Modified analytical technique for the determination of trace organics in water using dynamic headspace and gas chromatography-mass spectrometry

Abstract

In this paper we report a modified variant of the purge-and-trap gas chromatographic analysis of volatile organic carbon compounds in water. Samples collected in all-glass 1-1 bottles are purged at 60°C for 1 h in an ultrapure helium gas stream using an open-loop arrangement. Volatile eluates are trapped onto selective adsorbents packed inside stainless-steel tubes connected in series. After stripping at a flow-rate of 100 ml min −1 for 60 min, the adsorbent tubes are disconnected, fitted with analytical desorption caps and sequentially desorbed for 10 min on a thermal desorber. The desorbed organics are trapped at −30°C on a packed cold trap prior to flash volatilisation of the volatiles across a fused-silica transfer line onto a capillary column. The method separates over 200 organic compounds within 40 min utilising flame ionisation and ion trap detection and is capable of quantitation down to 5 ng l −1 per component. The results of a case study on the Solent estuary in southern England are briefly summarised.