Tong He,Peng Lei Cui,Jing Liu,Cheng Feng,Jian Ping Wang
In this study, a type of magnetic photoaffinity-labeled activity-based protein profiling probe for sulfonamide drugs was first synthesized for the purpose of capturing the natural dihydropteroate synthase of Escherichia coli by using simple incubation and magnetic separation. After characterization of its identity with LC-ESI-MS/MS, this enzyme was used as a recognition reagent to develop a direct competitive pseudo-ELISA for the determination of the residues of 40 sulfonamides in pork. Because of the use of streptavidin-horseradish peroxidase and biotinylated horseradish peroxidase as a signal-amplified system, the limits of detection for the 40 drugs were in the range of 0.001–0.016 ng/mL. Compared to the steps in a conventional assay formation, the operation steps were the same, but the sensitivities increased 32–88-fold. Furthermore, the assay performances were better than the previously reported immunoassays performances for sulfonamides. Therefore, this method could be used as a practical tool for multiscreening the trace levels of sulfonamides residues in food samples.
Ge Lin Liu,Hao Zhe Hou,Yan Su,Yao Jia Peng,Yin Liang Wu,Jian Ping Wang
The residues of xylazine and its metabolite in foods of animal origin are dangerous to consumers, but there has been no enzyme-linked immunosorbent assay (ELISA) or ELISA-like method reported to determine them so far. In this study, molecularly imprinted microspheres with xylazine as the template were synthesized, and 2,6-dimethylaniline (the metabolite of xylazine) was used as a hapten to prepare a streptavidinated horseradish peroxidase-labeled conjugate. A direct competitive pseudo-ELISA was developed on a microplate for xylazine and 2,6-dimethylaniline in milk. Because biotinylated horseradish peroxidase was employed to enhance the signal, the limits of detection for xylazine (0.003 ng/mL) and 2,6-dimethylaniline (0.005 ng/mL) were increased by 16.7- and 14-fold, respectively, compared to a horseradish peroxidase-labeled conjugate. Moreover, this material may be reused three times. The analysis of milk samples was consistent with values obtained by liquid chromatography tandem mass spectrometry. This is the first paper reporting a molecularly imprinted polymer-based method for the determination of xylazine and its metabolites in food.
危险品化学品经营许可证（带存储）