Department of Chemistry, CEMMPRE, Faculty of Sciences and Technology, University of Coimbra, 3004-535 Coimbra, Portugal.
Department of Analytical Chemistry, Faculty of Pharmacy, "Iuliu Haţieganu" University of Medicine and Pharmacy, 400349 Cluj-Napoca, Romania.
Sensors (Basel). 2021 Feb 7;21(4):1161. doi: 10.3390/s21041161.
A novel hybrid composite of conductive poly(methylene blue) (PMB) and carbon nanotubes (CNT) was prepared for the detection of 5-aminosalicylic acid (5-ASA). Electrosynthesis of PMB with glassy carbon electrode (GCE) or with carbon nanotube modified GCE was done in ethaline deep eutectic solvent of choline chloride mixed with ethylene glycol and a 10% aqueous solution. Different sensor architectures were evaluated in a broad range of pH values in a Britton-Robinson (BR) buffer using electrochemical techniques, chronoamperometry (CA), and differential pulse voltammetry (DPV), to determine the optimum sensor configuration for 5-ASA sensing. Under optimal conditions, the best analytical performance was obtained with CNT/PMB/GCE in 0.04 M BR buffer pH 7.0 in the range 5-100 µM 5-ASA using the DPV method, with an excellent sensitivity of 9.84 μA cm μM (4.9 % RSD, = 5) and a detection limit (LOD) (3σ/slope) of 7.7 nM, outclassing most similar sensors found in the literature. The sensitivity of the same sensor obtained in CA (1.33 μA cm μM) under optimal conditions (pH 7.0, = +0.40 V) was lower than that obtained by DPV. Simultaneous detection of 5-ASA and its analogue, acetaminophen (APAP), was successfully realized, showing a catalytic effect towards the electro-oxidation of both analytes, lowering their oxidation overpotential, and enhancing the oxidation peak currents and peak-to-peak separation as compared with the unmodified electrode. The proposed method is simple, sensitive, easy to apply, and economical for routine analysis.
一种新型的导电聚亚甲蓝（PMB）和碳纳米管（CNT）的杂化复合材料被制备用于检测 5-氨基水杨酸（5-ASA）。在胆碱氯化物与乙二醇混合的乙腈深共熔溶剂中，使用玻碳电极（GCE）或经碳纳米管修饰的 GCE 进行 PMB 的电合成，并在 Britton-Robinson（BR）缓冲液中在较宽的 pH 值范围内使用电化学技术、计时安培法（CA）和差分脉冲伏安法（DPV）评估不同的传感器结构，以确定用于 5-ASA 传感的最佳传感器配置。在最佳条件下，在 0.04 M BR 缓冲液 pH 7.0 中，使用 DPV 法在 5-100 µM 5-ASA 范围内，CNT/PMB/GCE 获得了最佳分析性能，灵敏度为 9.84 μA cm μM（4.9 % RSD， = 5），检测限（LOD）（3σ/slope）为 7.7 nM，优于文献中大多数类似的传感器。在最佳条件下（pH 7.0， = +0.40 V），CA 获得的相同传感器的灵敏度（1.33 μA cm μM）低于 DPV 获得的灵敏度。成功实现了 5-ASA 和其类似物对乙酰氨基酚（APAP）的同时检测，对两种分析物的电氧化表现出催化作用，降低了它们的氧化过电位，并增强了氧化峰电流和峰-峰分离，与未修饰电极相比。该方法简单、灵敏、易于应用且经济实惠，适用于常规分析。
