Determination of Nonylphenol Ethoxylates and Octylphenol Ethoxylates in Environmental Samples Using ¹³C-Labeled Surrogate Compounds

Abstract

Alkylphenol polyethoxylates (APEOs) have been widely used as nonionic surfactants in a variety of industrial and commercial products. Typical compounds are nonylphenol polyethoxylates (NPEOs) and octylphenol polyethoxylates (OPEOs), which serve as precursors to nonylphenol (NP) and octylphenol (OP), respectively. NP and 4-t-OP are known to have endocrine disrupting effects on fish (medaka, Oryzias latipes), so it is important to know the concentrations of APEOs in the environment. Because the analytical characteristics of these compounds depend on the length of the ethoxy chain, it is necessary to use appropriate compounds as internal standards or surrogates. We synthesized two ¹³C-labeled surrogate compounds and used these compounds as internal standards to determine NPEOs and OPEOs by high-performance liquid chromatography (LC)–mass spectrometry. Method detection limits were 0.015 μg/L for NP (2)EO to 0.037 μg/L for NP(12)EO, and 0.011 μg/L for OP(3,6)EO to 0.024 μg/L for OP (4)EO. NPEO concentrations in water from a sewage treatment plant were less than 0.05–0.52 μg/L for final effluent and 1.2–15 μg/L for influent. OPEO concentrations were less than 0.05–0.15 μg/L for the final effluent and less than 0.05–1.1 μg/L for influent.