Application of magnetic molecularly imprinted polymer for extraction and determination of antihypertensive drugs from biological samples

Hypertension is a progressive cardiovascular syndrome with a variety of causes, including cardiovascular risk factors that can lead to changes in heart and blood vessel function and structure. Therefore, hypertension, as a chronic disease, has negative effects on human health and is the main cause of cardiovascular-disease related deaths, further increases disability-adjusted life year and death [1]. Valsartan (VAL) is a promising angiotensin II receptor blocker which is rapidly absorbed from GI tract after oral administration but suffers from the drawbacks of poor oral bioavailability of about 23% primarily due to its lack of solubility in the acid milieu of the GI tract [2]. For some of antihypertensive drugs a low level of concentration, normally in ng/mL occurs in human plasma after oral administration, posing problems for their detection and/or monitoring. A sensitive method should thus be established to detect these drugs in bodies of human beings. In this work, a rapid and simple method for the extraction and preconcentration of VAL in biological samples using magnetic molecularly imprinted polymer (MMIP) was developed. The superparamagnetic Fe3O4 particles prepared by the coprecipitation method were coated successively by SiO2, vinyl end groups and molecularly imprinted polymer (MIP) shells to afford a pomegranate-like core/shell superparamagnetic particle (Fe3O4@SiO2@MIP). Finally, the Fe3O4@SiO2@MIP particles were successfully applied to simultaneously enrich and separate VAL. The separation of VALwas reached in less than 5 min using a C18 column and an isocratic binary mobile phase (acetate buffer- pH 4: water (50:50, v/v)) with flow rate of 1.0 mL min−1. Influence variables such as Fe3O4@SiO2@MIP amount, volume of desorption solvent, pH and extraction time were screened. The significant variables were optimized by using a Box–Behnken design. At optimum conditions values of variables set as 12 mg sorbent, 1 mL methanol, pH = 3 and 18 min extraction time.