Enzyme-linked immunoassay based on imprinted microspheres for the detection of sulfamethazine residue

- A new method for preparation of sulfamethazine (SM2) imprinted microspheres had been reported.
- The developed MI-ELISA is the first report for SM2 in animal tissues.
- The MI-ELISA can serve as an effective screening tool in any routine laboratory.

This study attempts to develop an enzyme-linked immunoassay (ELISA) using a molecularly imprinted polymer (MIP) as an artificial recognition element. The MIP microspheres were prepared using precipitation polymerization with SM2 as the template molecule, methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross-linker. After the microspheres were coated in microtiter plate wells, the molecular imprinting ELISA (MI-ELISA) method was established based on the direct competition between free SM2 and horseradish peroxidase (HRP)-labelled SM2 in heterogeneous mode. The linear regression analysis data for the calibration curve showed a good linear relationship with a regression coefficient of 0.999 in the concentration range of 100 μg L−1-3200 μg L−1. Furthermore, following the selective solid-phase extraction (SPE) with bulk SM2 MIPs as the sorbent and MI-ELISA detection, the limits of detection and quantification were 6.8 μg kg−1 and 20.4 μg kg−1, respectively, for SM2 in swine muscle. For the first time, MI-ELISA combined with molecular imprinting SPE was developed to determine trace SM2 in real samples, and the results show that it can be a useful analytical tool for quick detection in residue analysis.