Determination of Erythromycin Based on Its Parallel Catalytic Hydrogen Wave in the Presence of Hydrogen Peroxide

In a KH2PO4-Na2HPO4 buffer medium of pH 6.81, a catalytic hydrogen wave of erythromycin was observed at the potential of -0.80 V (vs.SCE), and upon addition of H2O2, a sensitive parallel catalytic hydrogen wave was observed at the same potential with its peak current increased about 15 times. Based on this fact, a method for the determination of erythromycin by parallel catalytic hydrogen wave was proposed. Linear relationship between values of 2nd derivative of peak current and concentration of erythromycin was kept in the range of 1.0×10-7-2.6×10-5mol·L-1 with detection limit (3S/N) of 5.0×10-8mol·L-1. The proposed method was used in the determination of erythromycin in pharmaceutical preparation, giving values of recovery in the range of 92.5%-101%. In the determination of erythromycin in a tablet sample, value of RSD (n=7) found was 2.4%.