Determination of four carbamate pesticides in corn by cloud point extraction and high-performance liquid chromatography in the visible region based on their derivatization reaction.

A highly sensitive method for the determination of arprocarb (AC), carbofuran (CF), isoprocarb (IC), and fenobucarb (FC) is proposed. The method is based on alkaline hydrolysis of the four carbamate pesticides, and the resultant hydrolysis products are reacted with 4-aminoantipyrene (AP) to give four red color products. The colored compounds are enriched and separated by cloud point extraction (CPE) method, and the coacervate phase containing the compounds is determined with a high-performance liquid chromatography (HPLC) system in the visible region. AC, CF, IC, and FC were determined on the basis of a linear correlation between the signals of the colored compounds and the concentrations of the pesticides. The method is applied to determine the four pesticides in corn samples; the limits of detection are 2.0 x 10(-4) mg L(-1) for AC, CF, and IC and 5.0 x 10(-4) mg L(-1) for FC, with recoveries ranging between 84.8 and 93.0%, at spiking levels of 5 x 10(-3), 2 x 10(-2), and 0.2 mg kg(-1), respectively.