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 A 9 PE surfactants. We have monitored monthly CAPECs and the other A 9 PE 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 A 9 PE 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.