A rapid immunomagnetic-bead-based immunoassay for triazophos analysis

Abstract

An immunomagnetic-bead-based enzyme-linked immunosorbent assay (IMB-ELISA) was developed for detection of pesticides by using carboxyl functionalized magnetic Fe₃O₄ nanoparticles (CMNPs). The CMNPs were prepared by co-precipitation of Fe²⁺/Fe³⁺ with oleic acid as a surfactant and subsequent oxidation of CC into COOH by KMnO₄ solution in situ. Then, anti-pesticide (triazophos) monoclonal antibodies were directly bonded onto the magnetic nanoparticles, which significantly increased the sensitivity compared with classic ELISA. The detection limit was 0.10 ng mL⁻¹. Addition-recovery and high-precision experiments were performed on blank samples that were determined to be without triazophos. The average recovery rate for three types of samples (with each spiking concentration measured 5 times in parallel) ranged from 83.1% to 115.9%, with a relative standard deviation (RSD) of less than 10%, which meets the requirement of pesticide residue analysis. The application results were in accordance with the gas chromatography-mass spectrometry (GC-MS) method, suggesting that IMB-ELISA is rapid and reliable for pesticide detection.