Detection of thiamethoxam, flubendiamide and endosulphan residues in rice grains

Abstract

A method was standardized and developed for simultaneous detection of thiamethoxam, flubendiamide and endosulphan residues in rice grains. Detection of monocrotophos, deltamethrin, phosphamidon and dichlorvos was already developed in rice grains with the same instrumentation system. However, in this new methodology, extraction was done with acetonitrile and simultaneous liquid-liquid partitioning formed by adding anhydrous magnesium sulphate followed by a simple clean-up step known as dispersive solid-phase extraction. The final extracts were concentrated and made up the volume with HPLC grade acetonitrile. Detection of thiamethoxam, flubendiamide and endosulphan residues were estimated using reverse phase-high performance liquid chromatography (RP-HPLC) coupled with UV-VIS detection system and C18 column. The mobile phase of acetonitrile and water (90: 10, v/v) @ 0.5 ml/minflow rate was operated for the method with a retention time of 5 min. Thiamethoxam, flubendiamide and α-endosulphan and β-endosulphan were found to get the peaks at retention times of 1.95 min, 2.40 min, 3.39 min, and 3.90 min, respectively. The recovery of >80% was observed for all the three insecticides when samples were spiked with standard insecticides at fortification levels of 0.05, 0.10, 0.25, 0.50 and 1.00 mg/kg.