Selective Extraction Based on Molecular Imprinting Polymer for Determination Lorazepam in Pharmaceutical and Biological Samples

A new and selective method was evaluated for the separation and quantification of lorazepam in pharmaceutical and biological samples utilizing a molecularly imprinted polymer (MIP) as a solid-phase extraction adsorbent material. The molecularly imprinted polymer (MIP) was synthesized via free-radical polymerization with lorazepam as a template and acrylamide as a functional monomer. The synthesized polymers were characterized using UV-visible spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. The adsorption isotherm and Kinetic studies were applied to characterize the adsorption of lorazepam by the synthesized polymers; additionally, the selectivity and reusability of the molecularly imprinted polymer were evaluated. Several parameters affecting solid-phase extraction performance, including adsorbent mass, flow rate, sample pH, sample volume, and the type and volume of the elution solvent were optimized. The proposed approach offers a linear dynamic range of 0.025-0.8 mmol/L, with a correlation coefficient of 0.9990 for lorazepam. The detection and quantification limits were determined to be 0.63 and 2.09 μmol/L, respectively. The suggested approach was well validated for the extraction and quantification of lorazepam in pharmaceutical and biological samples, with recoveries between 95% and 101% and a relative standard deviation of less than 2.5%.