DETERMINATION OF POLY(ETHYLENE GLYCOL)S IN ENVIRONMENTAL-SAMPLES BY THE INDIRECT TENSAMMETRIC METHOD

Poly(ethylene glycol)s (PEGs) are one of major metabolic products of t he biodegradation of non-ionic surfactants (NS). Therefore, a method f or the determination of PEGs in mixtures of metabolic products of the biodegradation of NS would be useful in the control of the aquatic env ironment. In order to solve this problem, the indirect tensammetric me thod (ITM) combined with an adequate separation scheme was applied. Th e analytical signal in the ITM reacts additively on both PEGs and NS. Therefore, NS interfere with the determination of PEGs. In order to se parate NS, extraction with ethyl acetate was used, Sequential extracti on of the sample with chloroform resulted in the separation of PEGs. T he residue after evaporation of an aliquot or the whole chloroform pha se was analysed using the ITM. The recovery and precision were checked on the example of a PEG of M(r) 600. The recovery was 92 and 96% for 100 and 1000 mu g spikes of PEG, respectively and the relative standar d deviation was 5.6 and 3.4%, respectively. The problem of the choice of standard and the error related to this choice are discussed. The de veloped method was used for the determination of PEGs in mixtures form ed during the testing of the biodegradation of oxyethylated alcohols u nder the OECD Confirmatory Test and in die-away experiments on 'native ' NS of river water. In both cases PEGs mere found to be major metabol ic products, The method was also applied to the determination of PEGs in river water.