Routine analysis of alcohol and nonylphenol polyethoxylates in wastewater and sludge using liquid chromatography–electrospray mass spectrometry

A wide range of alcohol and nonylphenol polyethoxylates was determined by separation on a reversed-phase liquid chromatographic column, followed by electrospray ionisation-mass spectral analysis. The compounds were separated chromatographically according to their aliphatic chain length. The mass spectral analysis functioned as a second separation step during which homologues of the ethoxylates were separated according to their polyethoxylate chain length. In this manner a truly orthogonal separation was obtained. The compounds were detected as ammonium complexes. The analysis presented is capable of qualitative and quantitative determination of a large number of ethoxylates as well as their metabolites in a single run. The method was applied to many different sample types, ranging from primary and treated wastewater to sludge. Batches of 50 real samples were routinely analysed without the need for cleaning the mass spectrometer or regeneration of the column. By utilising the extracted mass chromatograms, detection limits of 1 to 10 μg/l could be obtained for individual compounds in water samples, while the detection limits were around 100 μg/kg in sludge, depending on the degree of pollution.