Determination of four kinds of carbamate pesticides by capillary zone electrophoresis with amperometric detection at a polyamide-modified carbon paste electrode

In this paper, a polyamide-modified carbon paste electrode in capillary zone electrophoresis with amperometric detection (CZE-AD) was firstly applied to the determination of four carbamate pesticides: fenobucarb, isoprocarb, metolcarb and carbaryl. The four carbamates were hydrolyzed in alkalescent aqueous solutions, resulting in the formation of 2-sec-butyl phenol, 2-isopropylphenol, m-cresol and alpha-naphthol, which could be determined by amperometry after capillary electrophoretic separation. Under the selected optimum conditions, the four analytes could be perfectly separated within 23 min. The linear ranges of 2-sec-butylphenol, 2-isopropylphenol and m-cresol were from 1.0 x 10(7) to 2.0 x 10(-5) mol L-1 and that of alpha-naphthol was from 2.0 x 10(-7) to 2.0 x 10(-5) mol L-1 and their detection limits were 3.0 x 10(-8), 3.0 x 10(-8), 3.0 x 10(-8) and 6.0 x 10(-8) mol L-1, respectively (S/N = 3). Fenobucarb, isoprocarb, metolcarb and carbaryl can be indirectly determined by this CZE-AD method with recovery of 105, 104, 110 and 98% and R.S.D. of 4, 3, 4 and 3%, respectively. Above results demonstrated that this method was of high sensitivity, good repeatability and could be used in the rapid determination of the pesticide residues. (c) 2006 Elsevier B.V. All rights reserved.