Purpald-functionalized biosensor for simultaneous electrochemical detection of ascorbic acid, uric acid, L-cysteine and lipoic acid

The polymer purpald (4-amino-3-hydrazino-5-mercapto-1,2,4-triazole) film on glassy carbon electrode (p-Purpald@GCE) was fabricated using purpald monomer by electropolymerization method, and the modified electrode was applied as a probe for the simultaneous sensing of ascorbic acid (AA), uric acid (UA), L-cysteine (L-Cys) and lipoic acid (LA). The modified p-Purpald@GCE was well characterized by Scanning electrode microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Cyclic Voltammetry (CV), Electrochemical impedance spectroscopy (EIS) and Differential Pulse Voltammetry (DPV) techniques. CV, EIS results were confirmed the good electrocatayst nature of p-Purpald@GCE. Independent and simultaneous detection of AA, UA, L-Cys, and LA ware performed by DPV method. For Independent detection, based on the oxidation current changes, we have calculated the limit detection (LOD) of 392, 137, 341 and 200 nM (LOD) = 3S/m) for AA, UA, L-Cys and LA, respectively. The simultaneous detection of AA, UA, L-Cys, and LA executed and LOD found to be 364, 132, 275 and 192 nM, respectively. The modified electrode shows the high selectivity towards AA, UA, L-Cys and LA even in the presence of high concentration of other interferences. The developed sensor technique will be useful for the sensitive and simultaneous detection of AA, UA, L-Cys, and LA in food and clinical samples.