title: Development of a direct competitive enzyme-linked immunosorbent assay for parathion residue in food samples.
abstract: A heterologous direct competitive enzyme-linked immunosorbent assay (ELISA) for parathion residue determination is described based on a monoclonal antibody and a new competitor. The effects of several physicochemical factors, such as methanol concentration, ionic strength, pH value, and sample matrix, on the performance of the ELISA were optimized for the sake of obtaining a satisfactory assay sensitivity. Results showed that when the assay medium was in the optimized condition (phosphate buffer solution [PBS] containing 10% [v/v] methanol and 0.2 mol/L NaCl at a pH value of 5.0), the sensitivity (estimated as the IC(50) value) and the limit of detection (LOD, estimated as the IC(10) value) were 1.19 and 0.08 ng/ml, respectively. The precision investigation indicated that the intraassay precision values all were below 10% and that the interassay precision values ranged from 4.89 to 19.12%. In addition, the developed ELISA showed a good linear correlation (r(2)=0.9962) to gas chromatography within the analyte's concentration range of 0.1 to 16 ng/ml. When applied to the fortified samples (parathion adding level: 5-15 microg/kg), the developed ELISA presented mean recoveries of 127.46, 122.52, 91.92, 124.01, 129.72, 99.37, and 87.17% for tomato, cucumber, banana, apple, orange, pear, and sugarcane, respectively. Results indicated that the established ELISA is a potential tool for parathion residue determination.
authors.affiliation: Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou 310029, China.
authors.forename: Wen-Jun
authors.initials: WJ
authors.lastname: Gui
authors.forename: Yi-Hua
authors.initials: YH
authors.lastname: Liu
authors.forename: Chun-Mei
authors.initials: CM
authors.lastname: Wang
authors.forename: Xiao
authors.initials: X
authors.lastname: Liang
authors.forename: Guo-Nian
authors.initials: GN
authors.lastname: Zhu
mesh_terms: D004797:Enzyme-Linked Immunosorbent Assay / Q000295:instrumentation / Q000379:methods*; D005504:Food Analysis / Q000295:instrumentation / Q000379:methods*; D005638:Fruit / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007306:Insecticides / Q000032:analysis* / Q000737:chemistry; D000432:Methanol; D015394:Molecular Structure; D009994:Osmolar Concentration; D010278:Parathion / Q000032:analysis* / Q000737:chemistry; D014675:Vegetables / Q000737:chemistry
chemical_list: D007306:Insecticides; D010278:Parathion; D000432:Methanol