Optimisation of a Gas Stripping Concentration Technique for Trace Organic Water Pollutants

Abstract

The application of gas stripping for the concentration prior to analysis of organic water pollutants at the parts per million and parts per billion level has been studied. Solutes are stripped from solution by a stream of inert gas and subsequently adsorbed onto active carbon from which surface they are taken up in a solvent for analysis. The method is shown to be applicable to the analysis of a wide range of compounds including pesticides and polychlorinated biphenyls. The effect of gas flowrate, the time of stripping, adsorbent particle size, and desorbing solvent on the percentage recovery of a range of organic compounds has been measured. Problems of contamination of aqueous solutions by absorption of atmospheric vapours prior to analysis are considered, and the analysis of a typical water sample is demonstrated.