Novel PVC Membrane Selective Electrode for the Determination of Etoricoxib in Pharmaceutical Preparations

The construction and general performance characteristics of novel potentiometric membrane sensors responsive to the etoricoxib are described. The sensors are based on the use of ion-pair complex of etoricoxib (ET) with Picric Acid Pc-H (ET- Pc-H) as exchange sites in a with different plasticizers dibutyl phthalate (DBP) (electrode B) tri-n-butyl phosphate (TBP) (electrode C), or dioctylphthalate (DOP) (electrode A). The electrodes show a fast, stable and near- Nernstian for the mono charge cation of ET over the concentration range 0.09 -42.96 mM at 25 °C over the pH range 5-14 with cationic slope of 56.8 ± 0.5 and 55.0 ± 0.5 per concentration decade for ET-B and ET-A electrodes respectively. The lower detection limit is 0.05 mM and 0.07 mM with the response time 15s in the same order of both electrodes. Selectivity coefficients of ET related to a number of interfering cations and some organic compounds were investigated. There are negligible interference caused by most of the investigated species. The direct determination of 0.5 - 20 mM of ET shows an average recovery of 99.62 - 102.40% and 100.27-102.61 a mean relative standard deviation 2.75-0.64 and 1.76- 0.41 for A and B electrodes respectively. The results obtained by determination of ET in tablets using the proposed electrodes which comparable favorably with those obtained by spectrophotometric method. Validation of the method shows the suitability of the electrodes for the determination of ET in pharmaceutical formulations.