Comparison of four commercial enzymatic assay kits for the analysis of organophosphate and carbamate insecticides in vegetables

Contamination of organophosphate and carbamate (OP/C) insecticides in vegetables is a serious problem in China. An increasing number of acute poisoning accidents caused by OP/C residues in vegetables have brought great concerns on food safety. Four OP/C commercial enzymatic assay kits were compared on their sensitivity (half maximum inhibition concentration, IC50), matrix interference (i.e., background noise), accuracy (i.e., recovery) and precision (i.e., standard deviations), assay stability, simplicity of analysis, and cost. This work is not to advocate one companyʹs products over others. Research intention is only to provide some useful information to potential users such as various characteristics on their performance and their particular applications of the four kits. The results showed that the four kit tests have various advantages. In general, kit 1 exhibited better precision, while kit 4 had better sensitivity. Kit 1 exhibited better recovery data for the organophosphates and kit 4 had better recoveries for the carbamates than the other kits. Kit 1, kit 3 and kit 4 were more stable than kit 2 under the same temperature condition. In addition, the operation of kit 4 was the easiest. According to the performance comparison results and the cost-effective factor, kit 1 and kit 4 were more suitable for the local market.