Electrochemical Determination of Nitrofurantoin based on a Conducting Polymer Composite Film-Modified Electrode

[[abstract]]本研究先將羧酸官能化奈米碳管(Carboxylic acid functionalized multi-walled carbon nanotube, 以M 表示) 修飾於網版印刷碳電極上(Screen-printed carbon electrode, 以S 表示)，接著進行過氧化處理，並將三聚氰胺(Melamine, ME) 以循環伏安法(Cyclic voltammetry, CV) 方式修飾至電極表面，即成功製備聚三聚氰胺複合薄膜修飾電極(S/M*/PME)，以進行硝基呋喃妥因(Nitrofurantoin, NFT) 分子的電化學檢測。實驗流程為將S/M*/PME 浸泡至NFT 溶液中，使NFT 吸附至電極上後，直接於原溶液中進行循環伏安法掃描。由實驗結果發現S/M*/PME 比其他修飾電極更可使NFT 還原電流大幅增加，推測電極於經過修飾奈米碳管且氧化及聚合導電高分子處理後，電極反應面積增加，且電極表面與分析物之間之作用力增強，使得NFT 還原電流訊號有增幅的效果。實驗條件最佳化後，發現NFT 於pH 7的水溶液下吸附可得到最佳的還原電流值，以差式脈衝伏安法 (Differential Pluse Voltammetry, DPV) 進行NFT 定量，此方法的靈敏度為46.65 A/M，線性範圍介於0.02-2 M，偵測極限為0.43 nM (S/N=3)。[[abstract]]In this study, we fabricated a nitrofurantoin (NFT) sensor based on a composite film-modified electrode containing carboxylic acid functionalized multi-walled carbon nanotube (MWCNT-COOH) and a thin electroactive poly(melamine) (PME) film. The oxidized state of MWCNT-COOH is more efficient for the PME film growth than the original MWCNT-COOH. The detection involved the immersion of the modified electrodes in NFT solution for 15 minutes, and then cyclic voltammetry was operated in the same solution. The electrochemical reduction peak was used as the analytical signal. In order to enhance the detection sensitivity, the parameters for detection of NFT the were optimized, including the concentration of MWCNT-COOH, the overoxidation potential, the overoxidation time, the detection electrolyte and the immersion time. It is observed that the as-prepared modified electrode (S/M*/PME) could adsorb NFT strongly. The reasons could be the interfacial π-π stacking and hydrogen bonding. The reduction current responses increase significantly at S/M*/PME as compared with bare SPCE. Under optimal differential pulse voltammetry (DPV) conditions, the proposed assay can be used to determine NFT in pH7.0 buffer solutions. The method sensitivity was 46.7 μA/μM, and a linear response in the range of 0.02-2 μM was obtained. The detection limit was 0.43 nM (S/N=3).[[note]]碩