Determination of lomefloxacin, an antibacterial drug, in pharmaceutical preparations based on its polarographic catalytic wave in the presence of 2-iodoacetamide

In a 0.125 mol/L phosphate (pH 6.6)/2.5 x 10(-4) mol/L 2-iodoacetamide solu tion, lomefloxacin yields a response of a polarographic catalytic current. The second-order derivative peak current of the catalytic wave of lomefloxa cin is proportional to its concentration in the range of 1.0 x 10(-8) - 1.0 x 10(-6) mol/L (r = 0.998). The sensitivity of the catalytic wave is 25-ti mes higher than that of the corresponding reduction wave for 5.0 x 10(-7) m ol/L lomefloxacin. The proposed method was applied to the determination of lomefloxacin in pharmaceutical preparations. The polarographic reduction wa ve is ascribed to a one-electron reduction of the C=C bond of lomefloxacin zwitterion accompanied by an acid-base equilibrium. The catalytic wave shou ld be caused by regeneration of the lomefloxacin molecule at electrode surf ace due to the one-electron reduction product being further oxidized by ele ctroreductive intermediate products of 2-iodoacetamide.