A stable and sensitive enzyme‐linked immunosorbent assay (ELISA) for the determination of metsulfuron‐methyl residues in foods

Abstract

A hapten of metsulfuron‐methyl was successfully designed and synthesized from 2‐methylester‐phenylsulfonamide and succinic anhydride, and the polyclonal antibody against metsulfuron‐methyl was prepared by immunization procedure with the hapten–bovine serum albumin conjugate. A stable and sensitive direct competitive enzyme‐linked immunosorbent assay (dcELISA) method had been developed under the optimal conditions. The sensitivity (IC50) was 37.03 ± 1.87 µg/L, and the detection line (IC15) was 1.57 ± 0.11 µg/L. Rice, wheat, oat, flaxseed, milk, and water were chosen to study the recovery test and the recovery rates were 83.11%–117.44% . The matrix effect was eliminated by a simple dilution of the sample extracts. The results from dcELISA were well agreement with the results from HPLC–MS. It was indicated that the developed method had good accuracy and stability. It could be applied for the detection of metsulfuron‐methyl residues. It was worth mentioning that the antibody could recognize metsulfuron‐methyl and tribenuron‐methyl with cross‐reactivities of 100% and 49.72%, respectively. In order to understand the cross‐reactivity, molecular modeling including molecular alignment and electrostatic potential surfaces were introduced. It was found that the special group of metsulfuron‐methyl played an important role, especially on C3 position of the phenyl group. Practical Application A stable, sensitive, and low‐cost dc ELISA method had been developed with good accuracy and applied in the determination of metsulfuron‐methyl in foods. Molecular simulation was introduced to understand the specificity between the antibody and the analyst. It was a good method to study the cross‐reactivity between the antibody and the analyst or analogue.