Development of Aspartic Acid Modified Waste Battery Electrode for Simultaneous Determination of Vitamin C, Paracetamol and Caffeine

Abstract

Vitamin C (VC) is regarded as the most important water soluble antioxidant in human plasma. Paracetamol (PA) and Caffeine (CA) are important analgesic and antipyretic agents. The fixed combination of VC, PA and CA is widely used for the treatment of common diseases such as headache, cold, fever, muscle aches, arthritis, toothaches etc. A modified waste battery (WB) electrode sensor has been developed using Aspartic acid (APA) as a trifunctional electrochemical sensor for simultaneous detection of VC, PA and CA. Cyclic voltammetry (CV), differential pulse voltammetry (DPV) and UV-Vis spectroscopy were used as detection techniques.

In this study, battery electrode and pencil graphite (PG) electrode were prepared from waste battery and pencil respectively. Then waste battery (WB), pencil graphite (PG), glassy carbon (GC), gold (Au) and platinum (Pt) electrodes were used as the working electrodes for the determination of VC, PA and CA. These electrodes were modified with APA by applying continuous potential cycle for 15 scans at a range of -0.3 to 1.8 V at 100 mVs-1. A ternary solution of VC, PA and CA was prepared and the CV and DPV were taken at the modified (WB, PG, GC, Au and Pt) electrodes. It is observed that the performances of modified WB and GC electrodes are better than that of the modified PG, Au, Pt electrodes. But the GC electrode is more costly than WB electrode.

The influence of pH has been studied by varying pH from 3 to 9. The detection was mostly favorable at pH 7. The effect of different scan rates has been discussed and the variation of peak current was plotted with the square root of scan rate. The peak current increases with the increase of square root of scan rates. The nearly proportionality of the peak current suggests that the peak current of the reactant at each redox reaction is controlled by diffusion process with some chemical complications.

The effects of bare and modified WB electrode on single, binary and ternary solution of VC, PA and CA have been studied carefully. CVs of the single solution of VC, PA and CA at bare WB electrode show the oxidation peaks at 0.27V, 0.51V and 1.44V respectively. But at modified WB electrode, they exhibit the oxidation peaks at 0.18V, 0.42V and 1.40V. At bare WB electrode, the ternary mixture of VC, PA and CA reveal two oxidation peaks at 0.49V and 1.44V. But the APA modified WB electrode shows three separated and well defined oxidation peaks at 0.18V, 0.42V and 1.40V. The peak intensity of APA modified electrode was higher than that of the bare WB electrode. Similar behavior has been observed in the DPV technique.

Quantitative analysis of VC, PA and CA has been carried out by DPV using APA modified WB electrode in a single, binary and ternary solution. In every cases, the peak currents of VC, PA and CA increased linearly with the increasing of their concentrations over the range of 1.0 mM to 5.0 mM. The APA modified WB electrode showed good selectivity as well as strong anti-interference activity for the determination of VC, PA and CA in binary and ternary mixture with excellent result. The limit of detection (LoD) has been calculated by signal-to-noise (S/N=3) ratio. In simultaneous detection, the LoDs for VC, PA and CA are 0.20 μmol L-1, 0.16 μmol L-1 and 0.33 μmol L-1 respectively at APA modified WB electrode. The sensitivities of VC, PA and CA are 54.4 μA/mM/cm2, 99.9 μA/mM/cm2 and 151.7 μA/mM/cm2 respectively at APA modified WB electrode.

APA modified WB electrode has been successfully used for the quantitative determination of VC, PA and CA in some commercial tablets of different pharmaceutical companies in Bangladesh. The results have been valided by UV-Vis spectroscopic method. The amount of VC, PA and CA in some well-established pharmaceutical (Square, ACI, Beximco, Glaxopharma, ACME, Opsonin, Aristopharma, Incepta etc) tablet samples have been found approximately same compared to the labeled value. But in some pharmaceutical companies (IBN Sina, Kemico, Shubatech, Novelta, Eskayef etc), the amount of VC, PA and CA have been found less compared to the labeled value in the tablets.