| Autor: |
Hosu O; 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., Barsan MM; Department of Chemistry, CEMMPRE, Faculty of Sciences and Technology, University of Coimbra, 3004-535 Coimbra, Portugal.; National Institute of Material Physics, 077125 Magurele, Romania., Săndulescu R; Department of Analytical Chemistry, Faculty of Pharmacy, 'Iuliu Haţieganu' University of Medicine and Pharmacy, 400349 Cluj-Napoca, Romania., Cristea C; Department of Analytical Chemistry, Faculty of Pharmacy, 'Iuliu Haţieganu' University of Medicine and Pharmacy, 400349 Cluj-Napoca, Romania., Brett CMA; Department of Chemistry, CEMMPRE, Faculty of Sciences and Technology, University of Coimbra, 3004-535 Coimbra, Portugal. |
| Abstrakt: |
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% v/v 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 DES /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 -2 μM -1 (4.9 % RSD, n = 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 -2 μM -1 ) under optimal conditions (pH 7.0, E app = +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. |
