Potentiometric Determination of Amlodipine Besilate and Valsartan Using Microsized and Polymeric Matrix Membrane Sensors

Two poly(vinyl chloride) matrix membrane electrodes responsive to some drugs affecting the cardiovascular system, Amlodipine besilate (AM) and Valsartan (VL), were developed, described and characterized. A microsized graphite selective sensor was investigated with dibutylsebacate (DBS) as a plasticizer in a polymeric matrix of carboxylated polyvinyl chloride (PVC-COOH) in case of (sensor 1). This sensor 1 was prepared using 2-hydroxy propyl β-cyclodextrin (2HP β-CD) as an ionophore. While sensor 2 preparation was based on precipitation technique with bathophenanthroline iron (II) as electroactive materials in poly(vinyl chloride) (PVC) matrix. Fast and stable Nernstian responses near 1×10-5 - 1×10-3 M for the two drugs over the pH range 3-6 and 7-9 for the two sensors, respectively, were obtained. The method was successively applied for the determination of AM and VL in presence of each others, in their pharmaceutical formulations and in human plasma samples. The percentages recoveries for the determination of the drugs by the proposed selective electrodes were 99.78 ± 0.38 %, 100.23 ± 0.44 %, for sensors 1 and 2, respectively. Statistical comparison between the results obtained by this method and those obtained by the official method and the reported method of the drugs was done and no significant difference was found.