APPLICATION OF AN INDIRECT TENSAMMETRIC METHOD FOR THE DETERMINATION OF NONIONIC SURFACTANTS IN SURFACE-WATER

Three alternative procedures for the determination of non-ionic surfac tants (NS) in surface water have been developed. The simplest one cons ists of the filtration of water samples, the extraction of NS with eth yl acetate, the evaporation of the solvent and the determination of NS using an indirect tensammetric method (ITM). The detection limit is 1 5 mu g l(-1). The procedure using gas-stripping separation of NS shows a detection limit of 1.5 mu g l(-1). Chlorophyll extracted from water plants causes a serious interference. Therefore the sample must be fi ltered before extraction. The extractive procedure shows good precisio n and recovery of spiked surfactants from river water samples. Compara tive studies of the newly developed and the classical BiAS procedures were performed. The ITM procedure shows a detection limit of two order s of magnitude better than the BiAS procedure. Therefore the required volume of water sample is reduced from 5000 to 100 ml. Due to the simp ler separation procedure the ITM is substantially less time-consuming, cheaper and requires no sophisticated equipment or well-trained staff . An additional advantage of the ITM compared with the BiAS procedure is the lower sensitivity to the choice of standard surfactant and the broader ''spectrum'' of NS that can be determined. The results of a ha lf year current analysis of NS in river water have been included.