Preconcentration of Nicotinamide Using Molecularly Imprinted Microspheres for Solid-phase Extraction with Determination by High-performance Liquid Chromatography

The determination of target molecules in complicated matrices such as biological samples is largely dependent on sample pretreatment. Molecularly imprinted solid-phase extraction (SPE), using molecularly imprinted polymers as the adsorbent, has been demonstrated to be effective for the selective enrichment of target molecules in biological samples. In this study, molecularly imprinted polymeric microspheres were fabricated by two-step swelling polymerization using polystyrene particles as seeds, nicotinamide as the template, methacrylic acid as a functional monomer, and ethylene glycol dimethacrylate as a cross-linker. The molecularly imprinted polymeric microspheres were packed into empty SPE cartridges, and the spiked urine and serum samples were loaded separately. After an initial washing and elution step, the effluents were analyzed by high-performance liquid chromatography (HPLC) using 1:9 methanol/0.05% phosphoric acid. The obtained molecularly imprinted polymeric microspheres were uniform, and the spherical particles were well distributed. The established method was validated, and the results showed that the method was linear from 0.499 to 19.96 mu gmL(-1). The limits of detection and quantification for nicotinamide were 0.3 and 0.9 mu gmL(-1), respectively. The relative standard deviations were 1.55 and 2.86% in urine and serum, respectively. The spiked recoveries of nicotinamide were 86.0-98.8% and 87.0-96.8% in urine and serum, respectively. The molecularly imprinted SPE and HPLC methods in this study are useful for the pretreatment and determination of the target compounds in these matrices.