(Digital Presentation) Development of a Low Cost Pencil Lead Electrode for Simultaneous Detection of Amoxicillin and Uric Acid

Abstract

Herein, we develop a low-cost pencil graphite (PG) by amine-functionalization and employed for the first time, as an electrochemical transducer for the detection of amoxicillin (AMX). The electrochemical characterization results revealed that amination enhanced 2.17 times surface area than bare PGE. The pH of supporting electrolyte solution significantly influenced the electrochemical response of AMX oxidation. Besides, the experimental data revealed that AMX oxidation is irreversible, and diffusion-controlled process. The cyclic voltammetry (CV) and differential pulse voltammetry (DPV) technique are applied to quantitative determination of AMX. From the constructed calibration plot, a linear range from 2.5 µM to 300 µM with a detection limit (LOD) of 1.1028 µM was obtained for APGE using CV. While a wide linearity of 1µM to 325 µM and a LOD of 0.0113 µM were achieved by using DPV. The electrode was then applied for the simultaneous quantification of AMX and UA. In simultaneous detection the LOD was estimated to 0.964 µM, and 0.8876 µM for AMX and UA, respectively. The sensor substrate was tested in the presence of different potential interfering agent such as fructose, ascorbic acid, valine, sucrose, proline, histidine, glutamic acid, glycine, serine, phenylalanine, aspartic acid, creatinine, arginine, ampicillin, Na+, K+, Ca2+, Cd2+, Cl-, SO4 2-, NO3 -, Zn2+, Ba2+, and Pd2+. Furthermore, how long the modified electrode can alive was checked and a satisfactory reproducibility up to 37 weeks was found. Finally, the sensor substrate was applied for real samples as example in pharmaceutical formulation, in spiked urine, and in cow urine.