The fabrication and performance characteristics of three novel potentiometric sensors for the determination of oxeladin citrate are described. The proposed sensors include a PVC plastic membrane sensor, a carbon paste sensor and a multiwalled carbon nanotube (MWCNT) composite coated copper wire sensor. The sensors are based on the oxeladin-phosphotungstate ion associate as electroactive material and dibutyl phthalate as solvent mediator. The developed sensors exhibited near nernstian slopes of 58.00 ± 0.22, 55.00 ± 0.69 and 57.8 ± 0.13 mV concentration decade-1 at 25 ºC, in the concentration ranges 5.96 × 10-6 - 1.00 × 10-2, 1.96 × 10-5 - 1.00 × 10-2 and 3.98 × 10-6 - 1.00 × 10-2 mol L-1 oxeladin citrate with limits of detection of 4.14 × 10-6, 8.58 × 10-6 and 2.51 × 10-6 mol L-1 oxeladin citrate for plastic membrane, carbon paste and MWCNT composite coated copper wire sensors, respectively. The proposed sensors exhibit good selectivity for oxeladin with respect to a large number of inorganic cations, sugars, amino acids and vitamins. The developed sensors were successfully applied for the potentiometric determination of oxeladin citrate in the pharmaceutical preparation (Paxeladine® capsules) in batch and flow injection conditions. The sensors were also applied for the determination of oxeladin citrate in human urine samples by using the standard addition method.
oxeladin citrate; potentiometry; flow injection; pharmaceutical formulation; human urine
