Synthesis of new molecularly imprinted polymers for selective extraction followed by solid phase determination of Lorazepam concentration in a pharmaceutical preparation

A molecularly imprinted polymerr (MIP) was produced and assessed as a selective sorbent for the solid-phase extraction (SPE) and detection of lorazepam (LRZ) in pharmaceutical formulations. The polymerr was produced by free radical bulk polymerrization with the template molecule, lorazepam, the functional monomer, isopropylacrylamide (IPA), the crosslinker, glycidyl methacrylate (GMA), and the radical initiator, benzoyl peroxide. The synthesized polymerr was evaluated by UV–Vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM), demonstrating the successful synthesis of the polymerr and the efficiency of the template removal. Adsorption isotherm and kinetic experiments revealed that the produced MIP had strong affinity and selective recognition ability for lorazepam. The key parameters of SPE such as sorbent mass, sample pH, sample volume, flow rate and elution conditions were methodically tuned to reach the maximal extraction efficiency. Under the optimal circumstances, the developed technique exhibited excellent linearity in the studied concentration range (R2 = 0.9990) with detection and quantification limits of 0.92 and 3.10 µmol L-1, respectively. The approach exhibited good accuracy and precision with recoveries in the range of 98.0–104.0% and relative standard deviations lower than 3.5%. The new MIP-SPE/UV–Vis method offers a simple, rapid, economical and highly selective approach for the measurement of Lorazepam in pharmaceutical samples.