Enhanced Competitive Chemiluminescent Enzyme Immunoassay for the Trace Detection of Insecticide Triazophos

A direct competitive chemiluminescent enzyme immunoassay (CLEIA) for triazophos was developed, which was based on the anti-THHe IgG monoclonal antibody and a heterogeneous enzyme tracer (THHu-HRP). Several components of chemiluminescent enhanced solution (CES) were optimized. The results showed that 1 mM of p-iodophenol, 0.625 mM of luminol, and 4 mM of H2O2 had the best performance. Based on the study of CES, the influence of several factors (assay buffer, blocking substance, and solvent) on the immunoassay was investigated. The sensitivity for detection, IC50 value was 0.87 ng/mL at a practical working concentration range between 0.04 ng/mL and 5 ng/mL and the limit of detection for triazophos was 0.063 ng/mL. The average recovery of triazophos added to lettuce, carrot, apple, water, and soil were 78.71%, 67.52%, 118.3%, 117.2%, and 122.0%, respectively. Finally, comparison between the methods of CLEIA and high-performance liquid chromatography-tandem mass spectrum (HPLC-MS/MS) was performed. The results obtained from CLEIA were in agreement with those of HPLC-MS/MS.