Accurate Determination of Carbaryl, Carbofuran and Carbendazim in Vegetables by Isotope Dilution Liquid Chromatography/Tandem Mass Spectrometry

Abstract

An analytical method for the accurate determination of carbamate pesticides, carbaryl, carbendazim, and carbofuran, in vegetables was established based on the isotope dilution liquid chromatography/tandem mass spectrometry (ID-LC/MS/MS) technique as a candidate reference method. For sample clean-up, a Carb/LC-NH2 solid-phase extraction (SPE) cartridge was employed to ensure an efficient recovery and color removal from the vegetable samples. Isotope analogues, 13C6-carbaryl, carbendazim-d4, and 13C6-carbofuran, were used as internal standards, respectively. This method was validated by measuring samples fortified with the three target analytes into vegetable samples and prepared homogeneous Korean cabbage powder samples in this laboratory. All results of the measured values agreed with the fortified values within their uncertainties. Repeatability and reproducibility of the method were both approximately 2%. As commercially available CRM contains only carbendazim, its content was analyzed by the developed method. The measured value of carbendazim in CRM was (0.0724 ± 0.0013) mg/kg agreeing with the certified value (0.074 ± 0.004) mg/kg. These validation data indicate the developed ID-LC/MS/MS method is reproducible, repeatable and reliable to be as a candidate reference method for accurate determination of carbamate pesticides in vegetables.