Abstract
A simple and fast equilibrium liquid-phase microextraction method based on shake-assisted ultrasound-enhanced emulsification liquid-liquid microextraction (SAUELLME) technique combined with ultra performance liquid chromatography (UPLC) with UV detection was developed for the preconcentration and determination of five endocrine-disrupting phenols (EDPs) in seawater samples and detergent samples. The EDPs studied were 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). For SAUELLME, dispersion of the fine droplets of a low density organic extraction solvent into the aqueous sample is formed by use of the first step shake- assisted for mixing, and then the fine droplets could extract target analytes toward equilibrium faster because of the shorter diffusion distance and larger surface area by ultrasound-enhanced emulsification. Different experimental parameters were controlled and the optimum conditions found were: 25 μL of 1-bromohexadecane as the extraction solvent, 5 ml water samples, 1 minute ultrasound extraction time, 10 seconds shake-assisted time, centrifugation for 3 min at 5000 rpm, 1g NaCl for ionic strength, no pH adjustment, centrifugation tube was lying on the center of ultrasonic bath system. The correlation coefficient (γ2 ) greater than 0.995 for calibration curve range. The limit of detection (LOD) was 0.5 to 2.8 ngmL-1, the limit of quantitation (LOQ) was 1.8 to 9.3 ngmL-1 and the relative standard deviation (RSD) ranged from 4.2 % to 10.3 % for seawater samples. The limit of detection (LOD) was 0.4 to 2.4 μgmL-1, the limit of quantitation (LOQ) was 1.6 to 8.2 μgmL-1 and the relative standard deviation (RSD) ranged from 4.7 % to 10.0 % for detergent samples. Applying proposed method to spiked seawater samples and detergent samples in order to determine matrix effects. The relative recovery was 96 % to 109 % for seawater samples and 81 % to 106 % for detergent samples.