麦迪霉素H_2O_2缔合/平行催化氢波的研究及其应用

Study on Association/Parallel Catalytic Hydrogen Wave in Midecamycin-Hydrogen Peroxide System and Its Application

报道了有机化合物极谱催化波的一种新类型———缔合 /平行催化氢波 .研究麦迪霉素 H2 O2 体系缔合 /平行催化氢波的结果表明 ,质子化麦迪霉素与H2 O2 形成缔合物 ,引起峰电位负移 ;麦迪霉素催化氢波被H2 O2 还原中间产物羟基自由基进一步催化 ,使峰电流显著增加 .求得麦迪霉素 H2 O2 缔合物的缔合比为 1∶1,表观缔合常数为 7.18.在 0 .15mol·L-1KH2 PO4 NaOH(pH 7.4) 0 .0 2mol·L-1H2 O2 支持电解质中 ,-1.5 9V (vs .SCE)处的缔合 /平行催化氢波二阶导数峰峰电流与麦迪霉素浓度在 2 .0× 10 -8～ 1.0× 10 -5mol·L-1范围内呈线性关系 ,检测限为 6× 10 -9mol·L-1.与麦迪霉素的催化氢波相比 ,该缔合 /平行催化氢波提高分析灵敏度两个数量级 .

A new type of polarographic catalytic wave of organic compound, termed as association/parallel catalytic hydrogen wave, has been reported. The association/parallel catalytic hydrogen wave with such characters as the negative shift of the peak potential and the great increase of the peak current in midecamycin-hydrogen peroxide system was studied. Here hydrogen peroxide as ligand formed an association complex with protonated midecamycin, which caused the peak potential of the catalytic hydrogen wave of midecamycin to shift negatively. Additionally, the great increase of the peak current was due to the further catalysis of the catalytic hydrogen wave by hydroxyl radical produced in the reduction of hydrogen peroxide at electrode. It was determined that the association ratio was 1∶1 and the apparent association constant was 7.18. In 0.15 mol·L -1 KH 2PO 4-NaOH (pH 7.4)-0.02 mol·L -1 H 2O 2 supporting electrolyte, the second-order derivative peak current of the association/parallel catalytic hydrogen wave with peak potential -1.59 V (vs. SCE) was proportional to the midecamycin concentration in the range of 2.0×10 -8～1.0×10 -5 mol·L -1. The detection limit was 6×10 -9 mol·L -1. The association/parallel catalytic hydrogen wave was two orders in magnitude higher than that of the corresponding catalytic hydrogen wave in analytical sensitivity.