This paper introduces the first electrochemical approach for the determination of Fexofenadine hydrochloride and Montelukast sodium as a combined form by constructing three new graphite electrodes coated with a polymeric membrane. The first electrode was constructed using ammonium molybdate reagent as an ion pair with fexofenadine cation for the determination of Fexofenadine drug, the second electrode was constructed using cobalt nitrate as an ion pair with montelukast anion for the determination of Montelukast drug, the third electrode was prepared by incorporating the two previously mentioned ion pairs in the same graphite sensor, which makes this sensor sensitive to each Fexofenadine and Montelukast drug. The coating material was a polymeric film comprises of Poly Vinyl Chloride (PVC), Di-butyl phthalate as a plasticizer (DBP), ion pairs of drugs with previously mentioned reagents. The electrodes showed a Nernstian response with a mean calibration graph slopes of [59.227, 28.430, (59.048, 28,643)] mv.decade−1 for the three pencil electrodes respectively, with detection limits 0.025 μM for Fexofenadine and 0.019 μM for Montelukast drug which makes this method outperforms the reported method for the determination of this combination. The electrodes work effectively over pH range (2–4.5) for Fexofenadine hydrochloride and (5–9.5) for Montelukast sodium. The influence of the proposed interfering species was negligible as shown by selectivity coefficient values. The effectiveness of the electrodes continued in a period of time (45–69) days. The suggested sensors demonstrated useful analytical features for the determination of both drugs in bulk powder, in laboratory prepared mixtures and their combined dosage form. We have validated the method following ICH protocol, and we have reached very significant results in terms of the linearity, accuracy, selectivity, and precision of the method.

中文翻译：

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新型笔形石墨电极，用于纯净，合成混合物和组合剂型中盐酸非索非那定和孟鲁司特钠的电位测定

本文介绍了第一种电化学方法，用于测定盐酸非索非那定和孟鲁司特钠的组合形式，方法是构建三个涂有聚合物膜的新石墨电极。第一个电极使用钼酸铵试剂作为离子对与非索非那定阳离子构建，用于测定非索非那定药物；第二个电极使用硝酸钴作为离子对与孟鲁司特阴离子用于测定孟鲁司特药物；制备第三个电极通过将两个先前提到的离子对并入同一石墨传感器中，使该传感器对非索非那定和孟鲁司特药物敏感。涂层材料是一种聚合物薄膜，包括聚氯乙烯（PVC），邻苯二甲酸二丁酯作为增塑剂（DBP），离子对药物与前面提到的试剂。电极显示三个神经电极的Nernstian响应，平均校正曲线图斜率分别为[59.227、28.430，（59.048、28,643）] mv.decade-1，Fexofenadine的检测限为0.025μM，Montelukast药物的检测限为0.019μM。使得该方法的性能优于报道的确定该组合的方法。盐酸非索非那定在pH范围（2-4.5）和孟鲁司特钠（5-9.5）的pH范围内均可有效工作。如选择性系数值所示，提议的干扰物质的影响可以忽略不计。电极的有效性持续了一段时间（45-69）天。建议的传感器展示了用于测定散装粉末中两种药物的有用分析功能，在实验室制备的混合物及其组合剂型中。我们已经验证了遵循ICH协议的方法，并且在方法的线性，准确性，选择性和准确性方面都取得了非常重要的成果。