Mixed Extractant-Dispersive Liquid Phase Microextraction Based on Solidification of Floating Organic Drop for Determination of S -phenylmercapturic Acid in Urine

Abstract

A method of dispersive liquid phase microextraction based on solidification of floating organic drop(SFO-DLLME) with mixed extractant by high performance liquid chromatography(HPLC) for the determination of S-phenylmercapturic acid(SPMA) in urine was established.Detailed research on the conditions of microextraction was evaluated in the experiment.An aliquot of 20 mL of urine sample was adjusted to pH 2.0 and 7.2 g NaCl was added to increase the ionic strength.Then,100 μL mixed solvent(1-dodecanol/chloroform,1.8 ∶ 1,V/V) as extractant and 100 μL methanol as dispersive agent were injected into sample solution.The solution was shaken to disperse the extractant.The extraction solvent could be floated on the surface of the solution with the help of centrifugation and solidified at -20 ℃.Then the solid organic phase was transferred to EP tube and melted at room temperature.The supernatant of mixed extraction solvent was injected into HPLC system for.The analytical method showed good linearity in the range of 0.025-1.25 mg/L SPMA.The detection limit was 0.019 mg/L.The intra-day and inter-day precisions(relative standard deviation,RSD) of the method were 2.2%-5.4% and 2.5%-6.1%,respectively.The method was applied for determination of SPMA in human urine with satisfactory results.The spiked recoveries ranged from 86.8%-99.9%.The method was simple,fast and suitable for batch analysis of SPMA in urine samples.