Polymeric Membrane Sensors for Batch and Flow Injection Potentiometric Determination of Procainamide

Three new potentiometric membrane sensors responsive to procainamide hydrochloride (PR) were constructed and their general performance characteristics were determined. The sensors were constructed from PR ion-association complexes with tetraphenylborate (NaTPB) (1), phosphomolybdic acid (PMA) (2) and phosphotungstic acid (PTA) (3) as exchange sites in a polyvinyl chloride (PVC) matrix. The sensors exhibited stable, rapid and near-Nernstian properties for PR at concentrations of $1\times 10^{{-2 }}$ – $4\times 10^{-6}$ , $1\times 10^{-2}- 5\times 10^{-6}$ , $1\times 10^{-2}$ – $6\times 10^{-6}$ M at 25 °C with cationic slopes of 58 ± 0.5, 57 ± 0.5 and 56 ± 0.5 (mV/decade) for sensor 1, 2 and 3 respectively. The response time of the sensors was 20s in the optimum pH range of 4-8. The sensors were used in steady state and flow injection mode (automated system). Method validation revealed the sensors have high selectivity, low detection limits, long life, wide dynamic ranges as well as high accuracy and precision. Direct determination of 5- $2000~\mu \text{g}$ /ml of PR in solution returned average recoveries of 98.5%, 99.0% and 98.5% and mean relative standard deviations of 1.6%, 1.6% and 1.8% at $200.0~\mu \text{g}$ /ml for sensor 1, 2 and 3 respectively. Further, detection of procainamide in spiked urine exhibited favorable relative standard deviation (1.60-1.76%) and high recovery (98.83-99.26%). The sensors were used as end-point indicators for titration of procainamide with NaTPB.