Analysis of alkylphenol ethoxylate metabolites in the aquatic environment using liquid chromatography-electrospray mass spectrometry

A quantitative method is described for the analysis of the metabolites of alkylphenol ethoxylate (APEO) surfactants in estuarine water and sediment samples using reversed-phase high-performance liquid chromatography with electrospray mass spectrometry detection. Nonyl- and octylphenols, nonyl- and octylphenol mono-, di-, and triethoxylates, halogenated nonylphenols, and nonylphenol ethoxycarboxylates were concentrated from water samples using a C18 solid-phase extraction procedure. A novel, continuous-flow, high-temperature, sonicated extraction system was developed to isolate APEO metabolites from sediment samples. Quantitative LC-MS was performed in the negative ion mode for nonylphenols, octylphenols, and halogenated nonylphenols and in the positive ion mode for nonyl- and octylphenol ethoxylates using selected ion monitoring with isotopically labeled surrogate standards. Recoveries for sediment and water analyses ranged between 78 and 94%, and detection limits for APEO metabolites were between 1 and 20 pg injected on column. This is a significant improvement over previously reported methods. Suppression of analyte response was encountered in the presence of matrix components in sediment samples, but this effect was eliminated by careful selection of surrogate and internal standards. Individual APEO metabolite concentrations of 1-320 ng/L and 5-2000 ng/g are reported for water and sediment samples, respectively, from Jamaica Bay, NY.