Alkaline Phosphatase–Triggered Immunoassay Based on Fluorogenic Reaction for Sensitive Detection of Acetochlor, Metolachlor, and Propisochlor

Enzyme-linked immunosorbent assay (ELISA), as an immunoassay platform, usually suffers from poor sensitivity due to the limited signal intensity. To overcome this obstacle, an alkaline phosphatase–triggered immunoassay based on fluorogenic reaction of o -phenylenediamine and ascorbic acid was developed for sensitive detection of chloroacetamide herbicides in corn. The new immunoassay revealed limits of detection (LODs) for acetochlor (ATC), metolachlor, and propisochlor of 1.19 ng/mL, 2.34 ng/mL, and 3.40 ng/mL, respectively. The average recoveries of the three chloroacetamide herbicides in corn sample were 88.4%, 91.8%, and 87.6%, respectively. Such fluorescent immunoassay via in situ formation of fluorescent signal from scratch provides a new strategy with excellent sensitivity in point-of-care test of chloroacetamide herbicides.