Comparison of Micelle-Mediated Extraction and Diazotized 2,4-Dimethoxyaniline Methods for the Simultaneous Determination of Carbamate Insecticides by HPLC-UV.

The feasibilities of two strategies for the simultaneous analysis of five carbamate insecticides (i.e. propoxur, carbofuran, carbaryl, isoprocarb, and promecarb) by high performance liquid chromatography (HPLC) have been investigated. The first method is the preconcentration strategy based on micelle-mediated extraction (MME) using sodium dodecyl sulfate. The second strategy uses chemical derivatization with 2,4-dimethoxyaniline (DMA) reagent before subjecting to HPLC. The parameters affecting the analysis were optimized. For MME, the optimum conditions were 4.0% (w/v) SDS in the presence of 5.0 mol L-1 HCl. Meanwhile, the DMA derivatization condition was 1.5 mmol L-1 DMA, 7 mmol L-1 NaNO2, and 50 mmol L-1 HCl, and 250 mmol L-1 NaOH for the hydrolysis of carbamates before their derivatization. The target carbamates and their derivatives were monitored at wavelengths of 270 and 380 nm for the MME and DMA derivatization methods, respectively. The capability of each developed method was compared in terms of separation time and limits of detection (LODs). The results show that the five studied insecticides were successfully separated within 8 min (DMA) and 27 min (MME), respectively. LODs of the insecticides obtained from DMA (0.01-0.04 mg L-1) were lower than those obtained from MME (0.1-0.7 mg L-1). The proposed DMA method is versaltile and superior to MME for the analysis of carbamate insecticides in tap water samples.