N-Methylsuccinimide in plasma and urine as a biomarker of exposure to N-methyl-2-pyrrolidone

Objective: N-Methyl-2-pyrrolidone (NMP) is a selective and powerful organic solvent. The aim of this study was to investigate whether the NMP metaboli te N-methylsuccinimide (MSI) in plasma and urine can be used as a biomarker of exposure to NMP. Methods: Six healthy subjects were exposed to 10, 25, and 50 mg NMP/m(3) in an exposure chamber for 8 h. The air levels were moni tored by XAD-7 solid sorbent sampling, and analysed by gas chromatography ( GC). Plasma and urine were sampled for two days following the exposure, and the levels of MSI were analysed by GC with mass spectrometric detection. R esults: The concentration of MSI in plasma and urine rose during the exposu re, and reached a peak at about 4 h after the end of the exposure. The conc entration then decayed according to a one-compartment model with a half-tim e of approximately 8 h. About 1% of the inhaled NMP was excreted in urine a s MSI. There were very close correlations between the NMP air levels and, o n the one hand, the MSI concentrations in plasma collected at the end of ex posure (r = 0.98), or the urinary MSI concentration collected during the la st 2 h of exposure (r = 0.96), on the other. Conclusions: MSI in plasma or urine is applicable as a biomarker of exposure to NMP. The concentration in plasma and urine mainly reflects the exposure over one day.