Environ. Sci. Technol. 1996, 30, 513-516
Determination of the Cross-Reactivities of Immunoassays: Effect of Common Cross-Reactants for Chlorpyrifos-ethyl in Water Matrices Using Magnetic Particle-Based ELISA ANNA OUBIN ˜ A, JORDI GASCO Ä N, AND D A M I AÅ B A R C E L O Ä * Department of Environmental Chemistry, CID-CSIC, c/ Jordi Girona, 18-26, 08034 Barcelona, Spain
A novel approach to assess the cross-reactivity of immunoassays in the simultaneous presence of potential cross-reactant analytes was reported. The magnetic particle-based ELISA for chlorpyrifos-ethyl was used as a model assay in various water matrices (distilled, ground, and estuarine) in the presence of other organophosphorus pesticides commonly applied: chlorpyrifos-methyl, pyridafenthion, diazinon, fenitrothion, azinphos-ethyl, dichlorvos, temephos, and fenthion. The interferences were studied at a fixed concentration of 0.5 µg/L chlorpyrifos-ethyl and varying concentrations of the common cross-reactants from 0.05 to 1000 µg/L. The method for determining cross-reactivities gave much lower values (25-50%) as compared to conventional methods. A slight variation (10.000 >10.000 >10.000
0.97 (6) 7.33 (7) 9.34 (8) 32.05 (8) 2524 (4) 3297 (7) >10.000 >10.000 >10.000
100 13.68 10.60 3.11 0.038 0.031 10.000
0.98 (4) 7.57 (7) 8.11 (8) 31.16 (5) 2318 (6) 2339 (9) >10.000 >10.000 >10.000
99.04 13.25 12.21 3.20 0.041 0.043 10.000
0.99(3) 8.00(2) 11.86 (7) 28.69 (6) 2732 (7) 2463 (2) >10.000 >10.000 >10.000
97.46 12.54 8.35 3.37 0.035 0.041
