AbstractThis report describes a method for obtaining the concentrations of the total and individual alcohol ethoxylate (AE) species in sewage treatment plant (STP) effluents by using electrospray liquid chromatography/mass spectrometry (LC/MS). This is a more advantageous method for quantitative analysis of AE in environmental matrices as compared with a previous thermospray LC/MS method. This new method is more sensitive, uses less solvents, utilizes a deuterated internal standard blend [C13D27O(CH2CH2O)nH, where n varies from 0 to 21 with an average of n=9], which corresponds more closely to the AE, and it is a more robust instrumental technique. In this report, we document the results for validation of the electrospray LC/MS method by spike recovery of AE from STP effluent and influent samples.