Electrocatalytic Determination of Ampicillin Using Carbon-Paste Electrode Modified with Ferrocendicarboxylic Acid

A carbon-paste electrode spiked with ferrocenedicarboxylic acid (FDCMCPE) was constructed by incorporation of ferrocenedicarboxylic acid in a graphite powder-paraffin oil matrix. It has been shown by direct current cyclic voltammetry and double-step chronoamperometry that this electrode can catalyze the oxidation of ampicillin (AMPC) in aqueous buffered solution. It has been found that under the optimum condition (pH 10.0) in cyclic voltammetry, the oxidation of AMPC occurred at a potential of about 480mV on the surface of the modified carbon-paste electrode. The kinetic parameters such as electron-transfer coefficient, , and rate constant for the chemical reaction between AMPC and redox sites in FDCMCPE were also determined using electrochemical approaches. Under the optimized conditions, the electrocatalytic oxidation peak current of AMPC showed two linear dynamic ranges with a detection limit of 0.67mol L-1 AMPC. The linear calibration was in the range of 2.34-30mol L-1 and 40-700mol L-1 AMPC using the differential pulse voltammetric method. Finally, this method was also examined as a selective, simple, and precise electrochemical sensor for the determination of AMPC in real samples such as drugs and urine.