Study of Oxytetracycline Using Chitosan-Modified Magnetic Molecularly Imprinted Polymers Combined With Surface-Enhanced Raman Spectroscopy

Human consumption of food contaminated with oxytetracycline (OTC) residues can lead to its accumulation in the body and cause harm. In this study, due to the trace residues of OTC in food, surface imprinting technology was employed to prepare oxytetracycline magnetic molecularly imprinted polymers (OTC-MMIPs). This was achieved using Fe 3 O 4 @SiO 2 as the core, modified with chitosan, and with OTC as the template molecule. OTC-MMIPs were used to adsorb OTC. After combining with AuNPs, the OTC-MMIPs@AuNPs composite was used to adsorb OTC, and then SERS was employed for detection. According to the kinetic adsorption experiment, the maximum adsorption capacity of OTC-MMIPs was 44.58 mg g −1 , with a 7% decrease in adsorption capacity observed after four cycles of reuse. Following the adsorption of OTC onto OTC-MMIPs@AuNPs, detection was performed using SERS. A linear relationship was established between the intensity of the characteristic peak at 1329 cm − 1 and the OTC concentration, achieving a detection limit of 6.67 × 10 −12 M. Furthermore, the method was validated in pure milk samples, the recovery rate ranges from 91.73% to 96.22%. These results demonstrate the feasibility of the proposed method for detecting OTC in pure milk.