High performance liquid chromatography determination of 4-nonylphenol,4-tert-octylphenol, and their short ethoxyl chain polyethoxylates in water samples using a microporous membrane liquid-liquid extraction sample pretreatment technique

Abstract

Microporous membrane liquid-liquid extraction (MMLLE) sample pretreatment, coupled with reversed-phase high performance liquid chromatography with fluorescence detection (HPLC-FLD) was proposed for the determination of alkylphenols (APs), including 4-nonylphenol (4-NP) and 4-tert-octylphenol (4-t-OP), and their short ethoxyl chain polyethoxylates (SEC-APEOs) in environmental aqueous samples. After MMLLE, 4-NP, 4-f-OP, and SEC-APEOs were trapped in hexane used as acceptor. The hexane with enriched analytes was purged to dryness with nitrogen gas. Methanol (0.6 mL) and then water (1.4 mL) were added to dissolve the residue and the analytes were subsequently focused onto a C18 precolumn prior to injection onto the analytical column for separation and detection by reversed-phase HPLC-FLD. The proposed procedure permits convenient determination of APs and SEC-APEOs, which have similar endocrine activity and appear as a single peak in reversed-phase HPLC. The detection limits for 4-NP and 4-t-OP were 0.1 and 0.05 μg/L, respectively. Four samples including tap water, river water, and effluent from a sewage treatment works water were analyzed by the proposed method and the recoveries at 0.5 μg/L spiked level were in the range of 74-110%.