Determination of endocrine-disrupting phenols in water samples by a new manual shaking-enhanced, ultrasound-assisted emulsification microextraction method

Abstract

Manual shaking-enhanced, ultrasound-assisted emulsification microextraction (MS-USAEME) combined with ultraperformance liquid chromatography (UPLC) with UV detection has been developed for the determination of five endocrine-disrupting phenols (EDPs) in seawater samples and detergent samples: 4-tert-butylphenol (4-t-BP), 4-cumylphenol (4-CP), 4-tert-octylphenol (4-t-OP), 2,4-di-tert-butylphenol (2,4-di-t-BP) and 4-nonylphenol (4-NP). Optimum conditions were found to be: 25 μL 1-bromohexadecane as extraction solvent, 5 mL of aqueous sample and 1 g of NaCl to control the ionic strength; manual shaking for 10 s; ultrasonication for 1 min; centrifugation for 3 min at 5000 rpm (speed). For MS-USAEME, manual shaking for 10 s is essential for effective extraction when the ultrasonic extraction time is as brief as 1 min. The small volume of aqueous sample enhances the effect of manual shaking significantly. For seawater samples, the limit of detection (LOD) was 0.5–2.8 ng mL⁻¹, the limit of quantification (LOQ) was 1.8–9.3 ng mL⁻¹ with the relative standard deviation (RSD) in the range 4.2–10.3%. For detergent samples, the LOD was 0.4–2.4 ng mL⁻¹, LOQ was 1.6–8.2 ng mL⁻¹ and RSD 4.7–10.0%. The relative recovery was 96–109% for seawater samples and 81–106% for the detergent samples.