Determination of nonylphenol polyethoxylates and their lipophilic metabolites in sewage effluents by normal-phase high-performance liquid chromatography and fluorescence detection

Analytical procedures using normal-phase high-performance liquid chromatogr aphy (HPLC) with fluorescence detection, suitable for the routine determina tion of alkylphenol polyethoxylate (APnEO) surfactants and their lipophilic metabolites in sewage effluents at sub-microgram per litre level, have bee n developed. The parent nonylphenol polyethoxylates (NPnEO), covering oligo mer range of 1-18 ethoxy units per molecule, were extracted from water samp les using solid-phase extraction on graphitised carbon black (GCB), while t heir lipophilic metabolites, including nonylphenol monoethoxylate (NP1EO), nonylphenol diethoxylate (NP2EO) and nonylphenol (NP), were extracted by li quid-liquid extraction into n-hexane. The extracts were analysed by normal- phase HPLC using amino-silica columns and fluorescence detection at 228/305 nm. This allowed reliable quantitative determination of individual oligome rs down to 0.1 mu g/l. Analyses of sewage effluents collected in several se wage treatment plants of the Canton of Zurich, Switzerland, indicated that NPnEO occur at significant concentrations (96-430 mu g/l) despite the parti al ban introduced in 1986. Oligomer distributions found in analysed sewage samples revealed that the major part of toxic lipophilic metabolites, inclu ding NP, still originate from detergent-derived NPnEO.