Monitoring of Mandelic Acid as a Biomarker of Environmental and Occupational Exposures to Styrene

Styrene is an important constituent of widely used organic solvents in industries for production of various synthetic materials. The use of solid-phase extraction (SPE) has grown and is a fertile technique of sample preparation as it provides better results than those produced by liquidliquid extraction. In this study, SPE has been optimized, regarding sample pH, sample concentration, sample flow rate, elution solvent, washing solvent, sample volume, elution volume, and sorbent mass. Through experimental evaluation, a strong anion exchange silica cartridge has been found successful in simplifying sample preparation. The present approach proved that, mandelic acid, as a urinary metabolite of styrene, could be retained on solid phase based on specific interaction. Further study was employed 10% acetic acid to extract the analyte from spiked urine and gave a clean sample. In this study, a high performance liquid chromatography, using reverse-phase column was used. The isocratic run was done at a constant flow rate of 0.85 ml/min, the mobile phase was water/methanol/acetic acid and an ultra violate detector was used, setting at 225 nm. At the developed conditions the extraction recovery was exceeded 98%. The factors were evaluated statically and also validated with three different pools of spiked urine samples and showed a good reproducibility over six consecutive days as well as six within-day experiments.

Keywords
Solid phase extraction, Biological monitoring, Optimization, Chromatography