title: Septonex-tetraphenylborate screen-printed ion selective electrode for the potentiometric determination of Septonex in pharmaceutical preparations.
abstract: A screen-printed electrode (SPE) was fabricated for the determination of 1-(ethoxycarbonyl)pentadecyltrimethylammonium bromide (Septonex) based on the use of Septonex-tetraphenylborate as the electroactive substance, and o-nitrophenyloctylether (o-NPOE) as the plasticizing agent. The electrode passes a near-Nernstian cationic slope of 59.33 ± 0.85 mV from activity between pH values of 2 to 9 with a lower detection limit of 9×10(-7) M and response time of about 5 s and exhibits an adequate shelf-life of 6 months. The method was applied for the determination of Septonex in pharmaceutical preparations. A percentage recovery of 99.88% was obtained with RSD=1.24%. The electrode was successfully applied in the determination of Septonex in laboratory-prepared samples by direct potentiometric, calibration curve and standard addition methods. Potentiometric titration of Septonex with sodium tetraphenylborate and phosphotungstic acid as a titrant was monitored with the modified screen-printed electrode as an end-point indicator electrode. Selectivity coefficients for Septonex relative to a number of potential interfering substances were determined. The sensor was highly selective for Septonex over a large number of compounds. Selectivity coefficient data for some common ions show negligible interference; however, cetyltrimethylammonium bromide and iodide ions interfere significantly. The analytical usefulness of the proposed electrode was evaluated by its application in the determination of Septonex in laboratory-prepared pharmaceutical samples with satisfactory results. The results obtained with the fabricated sensor are comparable with those obtained by the British Pharmacopeia method.
authors.affiliation: Chemistry Department, Faculty of Science, Cairo University, Giza, Egypt. ggenidy@hotmail.com
authors.forename: Gehad G
authors.initials: GG
authors.lastname: Mohamed
authors.forename: M F
authors.initials: MF
authors.lastname: El-Shahat
authors.forename: A M
authors.initials: AM
authors.lastname: Al-Sabagh
authors.forename: M A
authors.initials: MA
authors.lastname: Migahed
authors.forename: Tamer Awad
authors.initials: TA
authors.lastname: Ali
mesh_terms: D006863:Hydrogen-Ion Concentration; D017736:Ion-Selective Electrodes; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D010772:Phosphotungstic Acid / Q000737:chemistry; D011199:Potentiometry / Q000379:methods*; D000644:Quaternary Ammonium Compounds / Q000032:analysis*; D013775:Tetraphenylborate / Q000737:chemistry*
chemical_list: D004364:Pharmaceutical Preparations; D000644:Quaternary Ammonium Compounds; C025729:Septonex; D010772:Phosphotungstic Acid; D013775:Tetraphenylborate