Occurrence and abundance of dicarboxylated metabolites of nonylphenol polyethoxylate surfactants in treated sewages

Very little is known on the occurrence and abundance in the environment of dicarboxylated metabolites (CAPECs) of AgPE surfactants. We have monitored monthly CAPECs and the other AgPE metabolites in effluents of five activated sludge sewage treatment plants (STPs) for 4 months. The analytical procedure is based on solid-phase extraction with a Carbograph 4 cartridge and liquid chromatography-mass spectrometry (MS) with an electrospray (ES) interface. On extracting 25 and 250 mL of respectively untreated and treated sewage samples, analyte recoveries ranged between 87 and 93% with RSDs no larger than 10%. Unexpectedly, data averaged on 20 samples of treated sewages showed that CAPECs were the dominant products of the AgPE biotransformation, accounting for 66% of all the metabolites leaving the plants. As a total, CA(8)PEC and CA(6)PEC represented 87% of the CAPEC class. On the average, CAPEC amounts having one ethoxy unit (CAPE(2)Cs) were almost double those of species having only a phenoxy acid moiety (CAPE(1)Cs). CAPEC species having more than four ethoxy units were never detected during our survey.