Derivatization LC/MS for the simultaneous determination of fatty alcohol and alcohol ethoxylate surfactants in water and wastewater samples

A new LC/MS method has been developed for the simultaneous measurement, in water and wastewater samples, of all species contained in commercial samples of linear type of alcohol ethoxylate (AE) surfactants including fatty alcohols. The method requires derivatization of the terminal hydroxyl of each surfactant species with 2-fluoro-N-methylpyridinium p-toluenesulfonate, which imparts a permanent cationic charge, allowing all species including the fatty alcohols and those with only one ethoxylate to be effectively detected by electrospray MS. Detection limits of typically <10 ppt for each individual species were attained in treated wastewater, in which total AE concentrations (combination of up to 114 individual species) are not expected to exceed 10 ppb. The method was validated for clean water as well as sewage influent and effluent samples.