Analysis of phenolic pollutants in human samples by high performance capillary electrophoresis based on pretreatment of ultrasound-assisted emulsification microextraction and solidification of floating organic droplet.

A novel, simple and rapid method, termed ultrasound-assisted emulsification microextraction and solidification of floating organic droplet (UAEM-SFO) coupled to high performance capillary electrophoresis (HPCE), was developed for preconcentration and analysis of five phenolic compounds (PCs) in human urine and blood samples. The proposed method is based on microextraction of target analytes in less-toxic organic solvent under assistance of ultrasound. A micro-droplet of less-toxic organic solvent floating on the surface of liquid samples in a sealed vial can be dispersed into sample solutions under the ultrasound frequency, solidified under ice bath, collected with a medicine spatula, molten at ambient temperature, and finally subjected to HPCE analysis. The parameters of UAEM-SFO procedure including type and volume of extraction solvent, extraction temperature, time of ultrasound-assisted extraction and centrifugation, sample pH, and ionic strength were optimized. The influence parameters on HPCE resolution such as pH, concentration of running buffer, applied voltage and injection time were also investigated. This method requires only 40 μL of 2-dodecanol extraction solvent and 8 min of pretreatment time. The enrichment factors of analytes were in the range of 114-172 and extraction recoveries (69-86%) were obtained. Good linearity was achieved for five analytes in the range of 0.05-100 μg L⁻¹ and the correlation coefficients ranged from 0.9934 to 0.9999. The limits of detection were 0.01 μg L⁻¹ for triclosan (TCS) and biophenol A (BPA), and 0.02 μg L⁻¹ for pentachlorophenol (PCP), 2,4-dichlorophenol (2,4-DCP) and 4-nonylphenol (4-NP) in urine samples, and 0.02 μg L⁻¹ for TCS and BPA, 0.04 μg L⁻¹ for PCP, 2,4-DCP and 4-NP in blood samples. The developed UAEM-SFO-HPCE method has a great potential in routine residual analysis of trace PCs in biological samples.