Potentiometric determination of nitrazepam in pharmaceutical dosage form and spiked plasma using a novel modified carbon paste electrode

Abstract

A newly prepared solid contact ion selective electrode based on polyvinyl chloride membrane has been optimized and developed for determining nitrazepam in its pure form and synthetically prepared tablet dosage form. The proposed electrode was fabricated based on zeolite modified carbon paste electrode as a solid contact acting as a support for the membrane of PVC containing the ion complex of nitrazepam-tetraphenyl borate as an electroactive material, and the plasticizer dibutyl phthalate. By improving the composition, the potentiometric properties were further enhanced, and the sensor achieved a Nernstian slope of 60.89 mV dec⁻¹. The sensor was effective for detecting nitrazepam in the concentration range of 1.0×10⁻⁷ to 1.0×10⁻² M, with a detection limit of 4.7×10⁻⁸ M. The sensor demonstrated excellent reversibility and reproducibility with a fast response time and application over a wide pH range. The developed electrode showed no significant effect when tested with various interfering species. It is successfully applied for accurate determination of nitrazepam in pure form, synthetically prepared tablet and spiked human plasma. The developed technique was validated and demonstrated high accuracy and precision. When compared statistically with the official method, there were no significant differences observed.