Development of an Enzyme-Linked Immunosorbent Assay for the Insecticide Thiamethoxam

Abstract

An enzyme-linked immunosorbent assay (ELISA) was developed for the neonicotinoid insecticide thiamethoxam, 3-(2-chlorothiazol-5-ylmethyl)-5-methyl-4-nitroimino-1,3,5-oxadiazinane. Three antisera were raised from rabbits immunized with the hapten-KLH conjugate. On the basis of the computational analysis of hapten candidates, the hapten with a spacer arm on the thiazolyl ring of thiamethoxam was synthesized to elicit thiamethoxam-specific antisera. The hapten was 3-[2-(2-carboxyethylthio)-5-ylmethyl]-5-methyl-4-nitroimino-1,3,5-oxadiazinane. Antisera were characterized with indirect competitive ELISA. Cross-reactivity and effects of organic solvents, pH, and ionic strengths were evaluated. The antiserum was specific for thiamethoxam and tolerant of up to 5% acetonitrile and 5% acetone. Various ionic strengths and pH values in the tested ranges had negligible effect on the assay performance. Under the optimized conditions, the half-maximal inhibition concentration (IC(50)) and the limit of detection were approximately 9.0 and 0.1 microg/L of thiamethoxam, respectively. ELISA analysis of stream and tap water samples showed an excellent correlation with the fortification levels.

Bismuth Film Electrode for the Cathodic Electrochemical Determination of Thiamethoxam

“…Since thiamethoxam is widely used as plant protecting agent in many countries, its determination at trace levels is an acute analytical problem. The methods that have been applied for its assay in agricultural and environmental samples involved high-performance liquid chromatography (HPLC) with diode-array [22,23] and mass-spectrometric [24,25] detection, as well as enzyme-linked immunosorbent assay [26]. The reduction mechanism of thiamethoxam at a dropping mercury electrode (DME) and its voltammetric determination either in model systems or thiamethoxam-treated samples, using glassy carbon (GCE) and static mercury drop electrodes (SMDE), were reported in our previous works [27,28].…”

Development of Monoclonal Antibody‐based Enzyme‐linked Immunosorbent Assay to the Estrogen Diethylstilbestrol

“…Chemical effects on assay performance were evaluated, which included: ionic strength, pH and organic solvent. As well known 32,35,36 those factors can affect assay to different degrees. We studied those factors for the application of immunoassay to the analysis of DES residue, and the good recovery of DES in water samples showed that the assay can be used for the determination of DES residues in water, but further work is needed to validate this assay with other matrices.…”

Review on Current Analytical Methods with Chromatographic and Nonchromatographic Techniques for New Generation Insecticide Neonicotinoids

“…Watanabe et al (2001) and Kim et al (2004) developed monoclonal antibody (MoAb) specific to imidacloprid, and constructed ELISA that is 5-fold to 20-fold more sensitive than that obtained using PoAb. In addition to imidacloprid, ELISA using MoAb specific to acetamiprid (Watanabe et al, 2001) and thiamethoxam (Kim et al, 2003(Kim et al, , 2006 were also developed. As described above, ELISA uses highly specific antigen-antibody reaction.…”