Determination of carbamates in soils by liquid chromatography coupled with on-line postcolumn UV irradiation and chemiluminescence detection

In this study, high performance liquid chromatography (HPLC) coupled with a simple and fast sample pre-treatment based on the use of the UV-irradiation in a simple continuous flow system for the chemiluminescent quantification of pesticide carbamates in soils was developed and validated. HPLC was used to separate thiodicarb, bendiocarb and carbaryl in soil extracts. The eluates emerging from the column tail were mixed with an alkaline solution of Co2+ in EDTA and irradiated with UV light to induce photolysis of the carbamates, in order to obtain free radicals and other reactive species capable of oxidizing luminol and producing photoinduced chemiluminescence (PICL) as a result. Measurements of CL intensity were plotted as a function of time to obtain chromatographic peaks. Under the optimum operating conditions for the combined HPLC-PICL system, CL peak areas were linearly related to analyte concentrations. The limit of detection were 0.05 mg L-1 for thiodicarb, 0.09 mg L-1 for bendiocarb and 0.17 mg L-1 for carbaryl. A simple extraction procedure using 98% methanol as solvent ensured complete dissolution of the analytes in spiked soils with recoveries from 87 to 120%. The proposed method is a simple, fast, accurate choice for quantifying the target pesticides in soils. (C) 2018 Production and hosting by Elsevier B.V. on behalf of King Saud University.