Determination of nonionic polyethoxylate surfactants in wastewater and sludge samples of sewage treatment plants by liquid chromatography-mass spectrometry

An analytical method is proposed in order to determine the major nonionic s urfactants, octylphenolpolyethoxylates (OPEOs), nonylphenolpolyethoxylates (NPEOs) and aliphatic alcoholpolyethoxylates (AEOs), and their metabolites, nonylphenol and octylphenol in wastewater and sludge samples of sewage tre atment plants. This method involved a Soxtec extraction step and a solid ph ase extraction step for the nonionic surfactant extraction from sludge and wastewater samples, respectively. With both methodologies, all recovery val ues were higher than 70 %. Quantitation and identification of individual co mpound were carried out by liquid chromatography-mass spectrometry (LC/MS) using electrospray (ESP) as ionization mode. Reverse phase LC chromatograph y allowed the elution of all oligomer constituents of each homolog componen t into a single peak. Gathering all the oligomers into a single peak increa sed the peak intensity and provided a way to determine low concentration of APEOs and AEOs in different environmental matrices. Information on the oli gomers distribution of APEOs and AEOs could be obtained by the extraction o f selected m/z ions from the TIC chromatograms. Positive ESP LC/MS analyses of AEOs and APEOs yielded primary pseudo-molecular ions of the [M + Na](+) type for each oligomer. The negative ionization mode allowed the determina tion of the two metabolites, nonylphenol and octylphenol, characterized by the pseudo molecular [M-H](-) ion. Limits of detection achieved were 0.1 mu g/L in wastewater sample and 10 ng/g in sludge samples. The developed LC-ES P/MS method was applied to the analysis of wastewater and sludge samples of two sewage treatment plants located in Orleans (France).