The voltammetric behaviour of diclofenac and mefenamic acid at a screen printed carbon electrode is very similar and both compounds share a similar molecular structure to that of diphenylamine. In each case on repeated scanning, an electroactive film is deposited due to the polymerisation of either of the molecules. The resultant film adheres to the electrode and is stable in aqueous solution for both diclofenac and mefenamic acid. This film formation is unique to a carbon electrode as no layers were found to form on Pt or Au. The formal potential of the confined layer shifts with pH, with a slope of about -59 mV/pH unit. Such layers will prevent the multiple use of the electrode in quantitative analysis unless it is cleaned between runs. A model based on the polymer formation from a diphenylamine backbone is proposed.

中文翻译：

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芬那酸伏安法的批判性分析：双氯芬酸和甲芬那酸电活性膜形成的证据


双氯芬酸和甲芬那酸在丝网印刷碳电极上的伏安行为非常相似，两种化合物具有与二苯胺相似的分子结构。在每种情况下，在重复扫描时，由于任一分子的聚合，都会沉积一层电活性膜。所得薄膜粘附在电极上，在双氯芬酸和甲芬那酸的水溶液中均保持稳定。这种成膜是碳电极独有的，因为没有发现在 Pt 或 Au 上形成层。受限层的正式电位随 pH 值而变化，斜率约为 -59 mV/pH 单位。这些层将阻止电极在定量分析中多次使用，除非在两次运行之间对其进行清洁。提出了一种基于二苯胺主链聚合物形成的模型。