Chemistry Department, Faculty of Science, Cairo University, Giza, Egypt.
Analyst. 2011 Apr 7;136(7):1488-95. doi: 10.1039/c0an00662a. Epub 2011 Feb 2.
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.
基于使用 1-（乙氧羰基）十五烷基三甲基溴化铵（Septonex）-四苯硼酸盐作为电活性物质，邻硝基辛醚（o-NPOE）作为增塑剂，制备了用于测定 1-（乙氧羰基）十五烷基三甲基溴化铵（Septonex）的丝网印刷电极（SPE）。该电极在 pH 值为 2 至 9 之间的活性范围内具有近 Nernst 阳离子斜率为 59.33 ± 0.85 mV，检测下限为 9×10(-7) M，响应时间约为 5 s，且具有长达 6 个月的合适保质期。该方法用于测定药物制剂中的 Septonex。通过直接电位法、校准曲线和标准加入法，回收率为 99.88%，RSD=1.24%。该电极成功应用于实验室制备样品中 Septonex 的测定，通过修饰后的丝网印刷电极作为终点指示电极，监测与四苯硼酸钠和磷钨酸作为滴定剂的 Septonex 的电位滴定。测定了相对于许多潜在干扰物质的 Septonex 的选择性系数。该传感器对大量化合物具有高选择性。对一些常见离子的选择性系数数据表明几乎没有干扰；然而，十六烷基三甲基溴化铵和碘化物离子有明显干扰。通过将提出的电极应用于实验室制备的药物样品中测定 Septonex，评估了该传感器的分析有用性，结果令人满意。所得到的结果与英国药典方法相当。
