Preconcentration and spectrofluorimetric determination of Valsartan in biological samples

Valsartan is a potent, orally active nonpeptide tetrazole derivative which causes reduction in blood pressure and anis used in treatment of hypertension. Valsartan is 3-methyll-2-[pentanoyl-[ [4-[2-(2H-tetrazoyl-5yl) phenyl] phenyl] methyl] amino] butanoic acid, with empirical formula of C24H29N5O3. It is not extensively metabolized and is mainly excreted by non-renal routes [1]. Although, several methods have been reported for determination of valsartan in biological systems mostly based on chromatographic methods [2, 3], but there is still the need to develope more sensitive methods with lower analysis cost and higher speed in the deterimantion. In this study, a spectrofluorimetric method has been developed for the determination of valsartan at λem= 380 nm (λex= 220 nm) after its extraction using a magnetic solid phase extraction (MSPE) method. Magnetic graphene oxide nanocomposite was used as the sorbent in MSPE. Graphene oxide was obtained using Hummer’s method with minor modifications and was further modified with iron oxides magnetic nanoparticles using a precipitation method. Various parameters which could affect the extraction efficiency were optimized. The results showed that under the optimized conditions (solution pH, 3.0; sorption time, 15 min; MGO amount, 150 mg) removal percent values more than 97% were achievable. The desorption step optimization experiments are underway.