Determination of volatile organic halogens in water after sorption on XAD-4 and thermal desorption

Abstract

The proposed method is based on the pre-concentration of organic water contaminants on solid sorbents, thermal desorption and, finally, a coulometric determination. The resin XAD-4 was selected for the pre-concentration of organics from water and the thermal desorption was carried out at 200 °C in a stream of purified argon. The compounds liberated were combusted in an empty quartz tube and the chlorides were determined by a coulometric argentometric titration to a pre-set potential. Good accuracy and precision were achieved both for solutions in distilled water and purified sea water. The average recovery was in the range 95–103%. The possibilities of thermal desorption in a stream of air and of storing the sorbent tube with organic compounds adsorbed on it were also investigated. This method was used successfully for the determination of volatile organic halogens in samples of tap, river and sea water.