New Validated Potentiometric Determination of Vasodilator Pentoxifylline in its Pharmaceutical Formulations and Biological Fluids

The construction and performance characteristics of pentoxifylline selective electrodes were developed. Two types of electrodes: plastic membrane I and coated wire II were constructed based on the incorporation of pentoxifylline with phosphotungstic acid (PTA). The influence of membrane composition, kind of plasticizer, pH of the test solution, soaking time, and foreign ions on the electrodes was investigated. The electrodes showed a Nernstain response with a mean calibration graph slope of 56.77 ± 0.19 and 55.76 ± 0.71 mV decade^‐1 at 25 °C for electrode I and II respectively, over pentoxifylline concentration range from 1.0 × 10^‐5‐1.0 × 10^‐2 and 9.0 × 10^‐6‐1.0 × 10^‐2 mol L^‐1, with detection limits 4.89 × 10^‐6 and 3.90 × 10^‐6 mol L^‐1 for electrode I and II, respectively. The pH range of the constructed electrodes was 4‐6. Interferences from common cations, alkaloids, sugars, amino acids and drug excipients were reported. The results obtained by the proposed electrodes were also applied successfully to the determination of the drug in its pharmaceutical preparations and biological fluids.