title: 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.
authors.affiliation: Department of Molecular Biosciences and Bioengineering, University of Hawaii at Manoa, Honolulu, Hawaii 96822, USA.
authors.forename: Hee-Joo
authors.initials: HJ
authors.lastname: Kim
authors.forename: Shangzhong
authors.initials: S
authors.lastname: Liu
authors.forename: Young-Soo
authors.initials: YS
authors.lastname: Keum
authors.forename: Qing X
authors.initials: QX
authors.lastname: Li
mesh_terms: D000818:Animals; D000918:Antibody Specificity; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D006241:Haptens / Q000737:chemistry / Q000276:immunology; D006433:Hemocyanins / Q000276:immunology; D007106:Immune Sera / Q000276:immunology; D007306:Insecticides / Q000032:analysis*; D008958:Models, Molecular; D015394:Molecular Structure; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000032:analysis* / Q000737:chemistry / Q000276:immunology; D010078:Oxazines / Q000032:analysis* / Q000737:chemistry / Q000276:immunology; D011817:Rabbits; D000077922:Thiamethoxam; D013844:Thiazoles; D014873:Water Pollutants / Q000032:analysis
chemical_list: D006241:Haptens; D007106:Immune Sera; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; D010078:Oxazines; D013844:Thiazoles; D014873:Water Pollutants; D000077922:Thiamethoxam; D006433:Hemocyanins; C032808:keyhole-limpet hemocyanin