Occurrence of Alkylphenoxyacetic Acids in Canadian Sewage Treatment Plant Effluents

Abstract

Abstract Alkylphenoxyacetic acids such as 4-tert-octylphenoxyacetic acid (OP1EC) and nonylphenoxyacetic acid (NF1EC) are metabolites of non-ionic surfactants derived from the ethoxylation of 4-tert-octylphenol (OP) and nonylphenol (NP). Although the occurrence of OP1EC and NP1EC was suspected in many Canadian sewage treatment plant effluents due to the extensive use of the alkylphenol ethoxylate surfactants and their degradation under sewage treatment conditions, the acids have never been reported due to the lack of authentic standards. In this work, OP1EC and NP1EC were synthesized by the condensation of OP and NP, respectively, with chloroacetic acid in the presence of a base. With these standards, the occurrence of OP1EC and NP1EC in Canadian sewage treatment plant effluents was confirmed for the first time. The level of OP1EC ranged from 0.18 to 1.2 μg/L and from 0.45 to 6.8 μg/L, in the primary and final effluents, respectively. In contrast, the level of NP1EC in the same sample was much higher and it ranged from 2.4 to 17.7 μg/L in the primary effluents and from 3.2 to 703 μg/L in the final effluents.