Abstract
In a 0.125 mol/L phosphate (pH 6.6)/2.5 × 10-4 mol/L 2-iodoacetamide solution, lomefloxacin yields a response of a polarographic catalytic current. The second-order derivative peak current of the catalytic wave of lomefloxacin is proportional to its concentration in the range of 1.0 × 10-8 - 1.0 × 10-6 mol/L (r = 0.998). The sensitivity of the catalytic wave is 25-times higher than that of the corresponding reduction wave for 5.0 × 10-7 mol/L lomefloxacin. The proposed method was applied to the determination of lomefloxacin in pharmaceutical preparations. The polarographic reduction wave is ascribed to a one-electron reduction of the C=C bond of lomefloxacin zwitterion accompanied by an acid-base equilibrium. The catalytic wave should be caused by regeneration of the lomefloxacin molecule at electrode surface due to the one-electron reduction product being further oxidized by electroreductive intermediate products of 2-iodoacetamide.
