Determination of short-chained poly(ethylene glycols) and ethylene glycol in environmental samples

A method for the determination of ethylene glycol (EG), di(ethylene glycol) (E2) and tri(ethylene glycol) (E3) in environmental samples (raw and treated sewage, river water) has been developed. These substances are important by-products in the biotransformation of non-ionic surfactants (NS). The method is based on sequential liquid-liquid extraction with ethyl acetate and chloroform (resulting in the separation of poly(ethylene glycols) (PEG) and EG from the water matrix), precipitation of long-chained PEG (PEGlch) with Dragendorff reagent, extraction of short-chained PEG (PEGsh) (EG, E2 and E3) from a filtrate with chloroform and the final determination using alternating current voltammetry. The precision of the method is 7.3%, the recovery 95% and a detection limit of 1.5 microg in the sample, i.e. 10 microg l(-1) was achieved. As evidenced by F and t tests, the developed method is equivalent to the indirect PEGsh determination by the difference approach where concentration of PEGsh is determined by the difference of the total PEG and PEGlch. The PEGsh fraction was found to be present in considerable concentrations in raw and treated sewage, river water, as well as being a major biotransformation by-product in the continuous flow activated sludge testing of fatty alcohol ethoxylates.