Determination of trihalomethanes in water using gas syringe injection of headspace vapours and electron-capture gas chromatography

Abstract

A simple, rapid electron-capture gas chromatographic method for the determination of trihalomethanes in water is described. Headspace vapours are withdrawn from the sample container at ambient temperature and injected by means of a gas-tight syringe with a valved needle, thus eliminating contamination problems associated with established liquid-liquid extraction and purge-and-trap methods. Simple precautions are adequate to minimise the effect of temperature fluctuations. Relative standard deviations of less than 2% were observed for treated river water samples, and the results were comparable to those of an established liquid-liquid extraction method.

The limits of detection are below 1 µg l^–1 and the response is linear up to at least 100 µg l^–1.