Establishment and Comparative Analysis of Enzyme-Linked Immunoassay and Time-Resolved Fluoroimmunoassay for the Determination of Trace Quinclorac in Environment

As a common herbicide in farmland, there has been wide concern over quinclorac residue because of its potential risks to the environment and human health. For the detection and monitoring of quinclorac residue in the environment, enzyme-linked immunoassay (ELISA) and time-resolved fluoroimmunoassay (TRFIA) were established. The half-maximal inhibition concentrations (IC50) of ELISA and TRFIA were 0.169 mg/L and 0.087 mg/L with a linear range (IC20–IC80) of 0.020–1.389 mg/L and 0.004–1.861 mg/L, respectively. Compared with ELISA, the limit of detection (LOD, IC20) and IC50 of TRFIA improved approximately 5-fold and 2-fold. The cross-reaction rates for the quinclorac analogs were less than 2%. The average recoveries of quinclorac in river water, paddy water, paddy soil, and brown rice samples were 77.3–106.1%, with RSDs of 1.7–12.5%. More importantly, the results of the two methods were consistent with that of the referenced method of UPLC-MS/MS (R2 > 0.98). ELISA and TRFIA both showed good detection performance and could meet the requirements of the quantitative determination of quinclorac. Therefore, the proposed ELISA and TRFIA could be applied to the rapid and sensitive detection and monitoring of quinclorac residue in the environment.