Isotope-dilution method for the determination of 1-vinyl-2-pyrrolidone-mercapturic acid as a potential human biomarker for 1-vinyl-2-pyrrolidone via online SPE ESI-LC/MS/MS in negative ionization mode.

We established and validated a specific and sensitive analytical method for the determination of 1-vinyl-2-pyrrolidone (VP) as 1-vinyl-2-pyrrolidone-mercapturic acid (VPMA) in urine using an electrospray liquid chromatography tandem mass spectrometry (ESI-LC/MS/MS) column switching method. An online solid phase extraction (SPE) for sample cleanup was performed by column switching to a restricted access material and back-flushing to the analytical column. A Phenomenex Luna C8 column was used for sample separation (150mm; ID 4,6mm; 3μm). D4-VPMA served as an isotope labeled internal standard and was detected in negative multiple-reaction monitoring (MRM) mode. The Limit of quantification (LOQ) for VPMA was 1.5μg/L, the intra-day precision of three concentrations (2μg/L, 75μg/L and 400μg/L) of spiked urine samples ranged from 2.7 to 7.3%, the inter-day precision from 3.4 to 14.4%. The accuracy ranged from 6.2 to 9.0%, for the intra-day experiments and from 0.3 to 6.9% for the inter-day experiments. The method was applied to urines of Sprague-Dawley rats exposed to VP as a proof of principle of VPMA as a potential biomarker.