Levels of 4-chloro-2-methylphenoxyacetic acid (MCPA) in the urine of northern italy occupationally exposed agricultural workers.
MCPA residues were assayed in 18 urine samples collected from northern Italy herbicide spraymen. Urine was collected within less than or equal to 24 hr from workshift start and kept at -20 degrees C until analysis. Twenty-five-milliliter urine specimens were ether-extracted at pH 1 and then the free MCPA was turned into its methyl ester. Detection and quantitation were carried out by high-resolution gas chromatography coupled with low-resolution mass spectrometry (hrGC-lrMS) run in the multiple ion detection (MID) mode. Specimen mass chromatograms were referred to MCPA methyl ester external standards. Detection thresholds were 25 and 10 ppb when S/N ratios of approximately 10 and 2.5, respectively, were adopted for the quantitation ion mass. Mean recovery was better than 80% over the full concentration range tested (10-1000 ppb). Urine analysis yielded the following results: eight outcomes fell in the 10-50 ppb range, five outcomes in the 50-150 ppb range, and five in the 150-500 ppb range.