Dispersive liquid-liquid microextraction for determinig urinary muconic acid as benzene biological indicator

Abstract

Monitoring of occupational exposure to chemicals is essential for assessing the workplace. In the case of hazardous and carcinogenic chemicals, such as benzene, occupational monitoring becomes even more crucial. Trans, trans muconic acid (t,t-MA) is one of the benzene urinary metabolites. Pretreatment methods for t,t-MA generally include liquid-liquid extraction and solid-phase extraction. Using dispersive liquid-liquid microextraction (DLLME) during sample preparation and extraction can reduce extraction costs and environmental impacts. Furthermore, the process is cost-effective and easy to operate. This study aimed to develop, optimize, and validate an analytical method for measuring t,t-MA concentration in urine matrix through DLLME combined with high-performance liquid chromatography. In this method, five variables including pH, the quantity of the extractant (μL) and the disperser (μL), salt (w/v, %), and the time of centrifugation (min) were optimized using response surface methodology with a central composite design approach and experimental data. The proposed DLLME was successfully applied to real samples of exposed workers to benzene with extraction efficiencies from 95.8 % to 102.4 %. The optimum conditions were pH=8, extractant solvent=300µL, disperser solvent=300µL, salt=3.4%, and centrifuge=3min. According to the result of this study, the proposed DLLME approach can be effectively applied to biomonitoring of individuals exposed to benzene.