Development of a Simple and Selective Method for Nicotinamide Determination in Human Plasma Samples by Magnetic Molecularly Imprinted Solid‐Phase Extraction Combined With UV–Visible Spectrophotometry

ABSTRACT A new method utilizing magnetic molecularly imprinted solid‐phase extraction (SPE) with ultraviolet–visible (UV–vis) spectrophotometry was developed to selectively extract, preconcentrate, and detect nicotinamide (NAM) in human plasma samples. To selectively adsorb NAM, novel magnetic molecularly imprinted polymers (Fe 3 O 4 @MIPs) were synthesized. The as‐prepared Fe 3 O 4 @MIPs exhibited a uniform core–shell structure with a polymer layer thickness of approximately 20 nm. The magnetic susceptibility of Fe 3 O 4 @MIPs was 7.7 emu/g, which can meet the need for rapid separation. Fe 3 O 4 @MIPs had an adsorption capacity of 411.8 mg/g, which was 232.7 mg/g larger than that of Fe 3 O 4 @NIPs. Moreover, Fe 3 O 4 @MIPs can achieve adsorption equilibrium within 15 min and exhibit good selectivity for NAM. On the basis of the above results, Fe 3 O 4 @MIPs were chosen as magnetic SPE adsorbent to selectively extract NAM from human plasma samples under the optimal experimental conditions, followed by concentration analysis using a UV–vis spectrophotometer. The validation experiment demonstrated that the proposed method had a broad linear range (50 ng/mL to 30 µg/mL), a low detection limit (8.2 ng/mL), and good recovery (92.8%–103.2%). Besides, the recovery of NAM by Fe 3 O 4 @MIPs remained above 85.2% even after five adsorption–desorption cycles. These results indicate that the proposed method, with its simplicity, rapidness, and low cost provides a potential prospect for extraction and accurate detection of targets in complicated samples.