Determination of Alcohol Ethoxylates derivatized with Naphthoyl Chloride, in Waste Water Treatment Plant Influent, Effluent and Sludge Samples by Liquid Chromatography Mass Spectrometry

A new analytical procedure for the determination of alcohol ethoxylates (AE) in environmental samples such as influents, effluents and sludge from waste water treatment plants (WWTPs) was developed. Although some work had been previously published on the detection of AE in water samples, this is the first paper that deals with AE in sludge. Alcohol ethoxylates were removed from water samples by sorption on polymeric discs followed by extraction with methanol. The methanol extracts were cleaned up with two alumina solid-phase extractions (SPE) at different conditions of solvent polarity, one before and the other after derivatization with naphthoyl chloride. A final polishing step was carried out on a Florisil SPE column. Liquid chromatography/mass spectrometry with electrospray ionization was used to quantify AE as naphthoyl derivatives. The detection limits for AE ethoxymers range from 0.07 to 0.005 μg/L in water samples. The method was applied to an Italian WWTP in order to follow the fate of AE during treatment, AE concentrations of 839 μg/L, 0.46 μg/L and 10.6 mg/kg were respectively found in the inlet, outlet and sludge samples. AE removals of each ethoxymer in the plant were in the range 99.6–100% and no difference was observed between high or low-mole ethoxymers and between AE with odd or even carbon chain lengths. An overall 99.7% removal was also determined on the mass balance of AE in the inlet, the outlet, and sludge of the plant.