Studies On The Methods For Fast Determination Of Organophosphate And Carbamate Pesticides Based On Enzyme Inhibition

Organophosphate and carbamate pesticides that are mainly used in agricultureshow low environmental persistence but display high acute toxicity. Theirpresence in water and food poses a potential hazard to human health. In generalthese compounds inhibit the acetylcholinesterase (AChE) participating innerve-impulse transmission. The inhibition mechanism, being very specific, hasled to the development of several analytical techniques for the identification andquantification of such pesticides on the basis of the inhibition ofacetylcholinesterase. In this paper, based on enzyme inhibition, a flow injectionsystem for fast determination of pesticides has been developed, and a pH-sensitivefluorescence probe was used as the pH indicator to detect the inhibition of theenzyme acetylcholinesterase. The percentage inhibition of enzyme activity wascorrelated to the pesticide concentration.In this paper, the detection limits of 3.5, 50, 12 and 25μg/l for carboruran,carbaryl, paraoxon and dichlorvos, were achieved respectively with an incubationtime of 10 min, which proved that our method was more sensitive than others inChina. A complete cycle of analysis, including incubation time, took 14 min, andthe sample through-put was 15/h.The detection system has been applied to the determination of carbofuran inspiked vegetable and fruit juices, and satisfactory recovery values were achieved.The influences of pH of samples on the detection of carbofuran are discussed. Forthe detection of the samples with low pH values, the pH need to be adjusted tohigher ones to obtaining satisfactory detection results.