Comparative Study of Three ELISA Formats forHeterologous Assay of Parathion

Four competitors which simulate parathion molecule were designed and synthesized,followed by testing the effect of assay format on the heterologous ELISA.Three types of assay formats,named the conjugate-coated (CC) format,antibody-coated (AC) format and indirect competitive (IC) format,were applied in the homologous or heterologous ELISA.Some factors,such as dosages of haptens and the antibody mentioned above,IC50 value and limit of detection of parathion,and recoveries of ELISA in different samples were compared to find the best assay format.The results showed that the used dosage of hapten and antibody in the heterologous ELISA were higher than that in the homologous ELISA,the heterologous ELISA greatly improved the sensitivity.Moreover,in the heterologous ELISA,the CC format had a relatively low reproducibility.While the AC format had the highest dosage of hapten and antibody in the three types formats,but had low sensitivity.It's found that the IC format had a preferable sensitivity and stable resistance to matrix effects.In conclusion,the IC format was the most suitable one in the heterologous ELISA.