Adsorptive stripping voltammetric determination of erythromycin at a pretreated glassy carbon electrode

The voltammetric behavior of the antibiotic erythromycin and its determinat ion was described. Erythromycin was found to give one oxidative peak by cyc lic voltammetry at a glassy carbon electrode which was electrochemically tr eated in 0.025 mol l(-1) NH3-NH4Cl (pH 9.0) solution for 6 min. The reverse cyclic voltammograms did not show any reductive peaks. An adsorptive strip ping voltammetric method for the determination of the antibiotic erythromyc in at an electrochemically pretreated glassy carbon electrode has been deve loped. Erythromycin was accumulated in NH3-NH4Cl (pH 9.0) medium at the pot ential of +0.2 V (vs. Ag/AgCl electrode) for a certain time and then determ ined by second differential anodic stripping voltammetry. The second-order differential peak current (e ") at +0.86 V, at a scan rate of 445 mV s(-1), was a linear function of concentration of erythromycin in the range 2.5 x 10(-8) similar to 3.5 x 10(-7) mol l(-1) (90 s preconcentration) and 1.2 x 10(-8) similar to 2.5 x 10(-7) mol l(-1) (120 s preconcentration), and the detection limit was 5.0 x 10(-9) mol l(-1) (4 min preconcentration). The me thod has been applied to the determination of erythromycin in commercial ta blets and spiked urine samples with satisfactory results. The relative stan dard deviation (n = 5) was less than 4.5%. (C) 2000 Elsevier Science B.V. A ll rights reserved.