Preparation of hollow porous molecularly imprinted and aluminum(III) doped silica nanospheres for extraction of the drugs valsartan and losartan prior to their quantitation by HPLC

Water compatible hollow porous molecularly imprinted nanospheres (HP-MINs) have been prepared for specific recognition and extraction of the blood pressure regulating drugs valsartan (VAL) and losartan (LOS). All synthetic steps were performed in aqueous medium and without consumption of organic solvents. The morphology and functionality of the materials were characterized by FT-IR, FE-SEM, and TEM techniques. The adsorption and selectivity experiments demonstrate that the HP-MINs possess a high binding capacity, fast kinetics, excellent water dispersibility and remarkable selectivity for VAL and LOS. The HP-MINs were utilized for dispersive solid phase extraction of VAL and LOS prior to their determination by HPLC-UV. Main variables and their interactions on extraction yield were optimized by multivariate analysis with least amount of experiments. Under optimized conditions, the method has a linear response in the 5-2000 mu g L-1 concentration range of both VAL and LOS. The limits of detection are 1.5 mu g L-1 for VAL and 1.4 mu g L-1 for LOS.