洛美沙星的吸附伏安特性及其应用

在Britton Robinson(pH8 80 ) 0 0 2mol·L- 1KCl底液中 ,洛美沙星 (Lomefloxacin ,简称LMF)在汞电极上有一线性扫描还原峰 ,峰电位Ep=- 1 4 0V (vs.Ag/AgCl) ,该峰具有明显的吸附性 .吸附粒子为LMF中性分子 ,测得LMF在汞电极上的饱和吸附量Гs=4 2 7× 10 - 11mol·cm- 2 ,每个LMF分子所占电极面积为 3 89nm2 ,LMF在汞电极上的吸附符合Langmuir吸附等温式 .测得吸附系数 β =2 2 9× 10 6,2 5℃时的吸附自由能ΔG =- 36 2 9kJ·mol- 1,电极反应电子数n =2 ,不可逆体系动力学参数αnα=1 84 ,表面电极反应速率常数ks=0 2 9s- 1,扩散系数D =7 38×10 - 7cm2 ·s- 1.建立了吸附溶出伏安法测定LMF的最佳条件 ,检出限为 5 0× 10 - 8mol·L- 1.

ADSORPTIVE VOLTAMMETRIC BEHAVIOR OF LOMEFLOXACIN AND ITS APPLICATION

In a supporting electrolyte containing Britton-Robinson (pH8.80)-0.02mol*L-1 KCl , a reduction peak of LMF is observed by linear-sweep voltammetry at Hg electrode. The peak shows a potential of -1.40V(vs.Ag/AgCl) and adsorptive characteri-stics. The adsorbed species is most probably the neutral molecular of LMF. The saturated adsorption amount of LMF at Hg electrode is 4.27×10-11 mol*cm-2 and every LMF molecule occupies an area of 3.89nm2. On the surface of the hanging mercury drop electrode, the adsorption of LMF obeys Langmuir adsorption isotherm. The adsorption coefficient β is 2.29×106, the Gibbs energy of adsorption ΔG is -36.29kJ*mol-1, the number of electrons transferred n is 2, the kinetics parameter αnα is 1.84, the rate constant ks of surface electrode reaction is 0.29s-1, and the diffusion coefficient D is 7.38×10-7 cm2*s-1. The detection limit of the adsorptive stripping voltammetry of LMF is 5.0×10-8 mol*L-1under optimized condition.