Analysis of diazepam residues in aquatic products based on magnetic molecularly imprinted polymers

This study successfully prepared an efficient magnetic molecularly imprinted polymer (MMIP) nanocomposite using carbon nanotubes as the carrier. A series of characterization techniques were employed to systematically investigate the structure of the prepared nanocomposite. Static adsorption, dynamic adsorption, and selective recognition experiments were conducted to evaluate the adsorption behavior of the nanocomposite. Subsequently, the material was employed as a selective sorbent in magnetic solid-phase extraction (MSPE) and combined with HPLC-MS/MS to develop a method for the determination of diazepam residues in fish samples. Under optimal experimental conditions, the method exhibited outstanding analytical performance: the limit of detection (LOD) and limit of quantification (LOQ) for diazepam were as low as 0.1 µg kg^-1 and 0.33 µg kg^-1, respectively, with recoveries ranging from 89.36% to 104.43% and relative standard deviations (RSD) of 1.22-5.30%. The satisfactory spiked recoveries and low RSD values indicate high sensitivity and good reproducibility. The strategy of using 2-chlorodiphenylketone as a dummy template constitutes an important highlight of this method, which fundamentally avoids potential false positives and quantification errors caused by template leakage in traditional molecular imprinting techniques. In summary, a magnetic molecularly imprinted polymer-based analytical method was established for the selective and accurate determination of diazepam residues in fish samples.