DETERMINATION OF NONIONIC SURFACTANTS ADSORBED ON PARTICLES OF SURFACE-WATER BY AN INDIRECT TENSAMMETRIC METHOD COMBINED WITH THE BIAS SEPARATION SCHEME

Procedures have been developed for the determination of non-ionic surf actants (NS) adsorbed on particles in water samples, NS dissolved in w ater and a total flux of NS (comprising both fractions). Two procedure s for the determination of NS adsorbed on particles were developed: di rect determination and a differential method. In the direct determinat ion (detection limit of 3 mu gl(-1)), NS adsorbed on particles are sep arated by filtration and subsequent extraction of NS adsorbed on parti cles with ethyl acetate. The further separation and quantification fol lows the separation scheme of the BiAS method (bismuth active substanc es) combined with the indirect tensammetric method (BiAS-ITM). In the differential approach (detection limit of 8 mu gl(-1)), the concentrat ion of NS in filtered water (as determined by the BiAS-ITM) is subtrac ted from the corresponding result for non-filtered water. The results for concentration of NS in non-filtered water, as determined by the Bi AS-ITM, represent a total flux of NS in river water (dissolved fractio n and fraction of NS adsorbed on particles). The detection limit of th e determination is 6 mu gl(-1). In the tested samples, NS adsorbed on particles ranged from 4% to 32% (average 20%) of total concentration o f NS in river water. The BiAS-ITM shows a fundamental advantage vs. th e indirect tensammetric method (ITM) used as a separate procedure in t he determination of NS adsorbed on particles or contained in non-filte red water samples, due to tolerance to chlorophyll. On the other hand, the ITM can be recommended for the determination of NS in filtered wa ter samples.