Analysis of N-methylcarbamates insecticides and some of their main metabolites in urine with liquid chromatography using diode array detection and electrospray mass spectrometry

Abstract

Commonly used N-methylcarbamates, i.e., aldicarb and carbofuran and some of their main metabolites as aldicarb sulphoxide and aldicarb sulphone for aldicarb and 3-hydroxycarbofuran for carbofuran were extracted from human urine by off-line solid phase extraction with graphite carbon and subsequently clean up with NH 2-modified silica. Analyte fractionation and quantification were performed by liquid chromatography (LC) with UV detection. The recovery efficiencies of the tested compounds yielded more than 81% at the fortification level of 0.05 μg/ml in urine and their relative standard deviations were between 6 and 16%. The detection limits of each compound ranged between 4 and 10 μg/l. This method involves confirmatory analysis by LC–electrospray mass spectrometry (MS) instrumentation equipped with a single quadrupole mass filter. MS data acquisition was performed by time-scheduled selected ion monitoring (SIM) program. Limits of detection giving values between 0.1 and 0.5 μg/l. Urine samples from a pest control operator were analyzed and the analytes were not found.