Abstract
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.
Highlights
Oxeladin citrate, 2-(2-diethylaminoethoxy)ethyl 2-ethyl2-phenylbutyrate dihydrogen citrate, CAS No 5243272-1 (Scheme 1), is a white or almost white crystalline powder soluble in water that exhibits polymorphism
The polished electrode surface was coated with the active membrane by quickly dipping the exposed end 6-8 times into the coating solution prepared by dissolving optimum ion associate composition previously described under plastic membrane composition, 5% ion associate (17.5 mg), 1% MWCNT (3.5 mg), 47% polyvinyl chloride (PVC) (164.5 mg) and 47% dibutyl phthalate (DBP) (164.5 mg), and allowing the film left on the wire to dry in air for about 1 min each time until a plastic film of approximately 1.0 mm thickness was formed
The results indicated that the electrode made by membrane with 5% oxeladin-PT ion associate exhibits the best performance characteristics
Summary
2-(2-diethylaminoethoxy)ethyl 2-ethyl2-phenylbutyrate dihydrogen citrate, CAS No 5243272-1 (Scheme 1), is a white or almost white crystalline powder soluble in water that exhibits polymorphism. Potentiometric methods with ion selective electrodes have proved to be effective for the analysis of pharmaceutical compounds and biological samples because these sensors offer the advantages of simple design, reasonable selectivity, fast response time, applicability to colored and turbid solutions and possible interfacing with automated and computerized systems.[9] Carbon nanotubes are widely used in several fields in material science It is a major component in nanotechnology.[10,11] The recent discovery of carbon nanotubes (CNTs) attracted much attention because of their dimensions and structural sensitive properties.[12] The nanotubes consisted of up to several tens of graphite shells (so called multiwalled carbon nanotubes, MWCNT) with adjacent shell separation of ca. The proposed sensors were used to determine oxeladin citrate in bulk, pharmaceutical formulation (Paxeladine® capsules) and human urine samples
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