Abstract
A sensitive, low-cost, and simple electrochemical sensor based on Zn-Al layered double hydroxide (Zn-Al LDH) combined with a polymer film of methyl red (PMR) to modify a GCE has been created for the first time. Using cyclic voltammetry (CV), the electrochemical characteristics of the newly fabricated sensor were investigated. The characterised PMR/Zn-Al LDH/GCE shows high electro-catalytic activity towards the vitamin C (AA) and aspirin (ASA) oxidation. Schematic fabrication of PMR/Zn-Al LDH/GCE for the determination of AA or ASA was presented. The new sensor demonstrated superior analytical efficiency for the simultaneous identification of AA and ASA traces in well-spaced anodic peaks, even in the presence of certain intervening species. According to experimental results, the fabricated sensor represented two well-separated oxidation peaks for AA and ASA oxidation with potential difference of 799 mV (vs. Ag/AgCl). The linear dependences of the anodic peak currents of AA and ASA on their concentrations in the ranges of 0.10-53.17 mu M are good. The detection limits of AA and ASA at the PMR/Zn-Al LDH/GCE were found to be 1.26 and 1.27 mu M, respectively. Meanwhile, the quantification limits of AA and ASA were calculated as 4.21 and 4.25 mu M, respectively. On other hand, the limit of detection (LODs) of AA and ASA oxidation were determined to be 0.47 and 0.21 mu M, respectively, according to DPV method. The effect of scan rate (100 to 800 mV/s) on the anodic peak currents of AA and ASA was examined. A sensing model mechanism has been suggested and discussed in detail. Finally, the proposed sensor displayed a good reproducibility, stability and selectivity. The developed sensor was eventually used to successfully detect AA and ASA in urine samples.