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(Nonylphenoxy)acetic acid (NP1EC) and (nonylphenoxy)ethoxy acetic acid (NP2EC) were determined in influents and effluents of mechanical-biological sewage treatment plants and in a polluted river. A characteristic set of isomers with differently branched nonyl substituents was identified by high-resolution gas chromatography/mass spectrometry (HRGC/MS). Quantitative determinations with high-performance liquid chromatography (HPLC) and HRGC achieved relative standard deviations better than 10%, and detection limits were about 1 μg/L. High concentrations of nonylphenoxy carboxylic acids were observed in secondary sewage effluents (71-330 μg/L), whereas nontreated sewage and primary effluents contained much lower levels (<1-17 μg/L). Considerable concentrations of nonylphenoxy carboxylic acids (2-116 μg/L) were found in a polluted Swiss river. Nonylphenoxy carboxylic acids are refractory metabolic products of nonylphenol polyethoxylates, which are commonly used nonionic surfactants.
Ahel et al. (Wed,) studied this question.