黄芩甙的极谱催化波研究及应用

Study and Application of Polarographic Catalytic Wave of Baicalin

在 0 .2 4mol/L混合酸 NaOH(Britton Robinson) (pH 2 .0 ) -8× 1 0 -3 mol/LKIO3 支持电解质中 ,黄芩甙产生一极谱催化波 ,峰电位为 -1 .2 0V(vs.SCE)。该波的一阶导数峰峰电流与黄芩甙浓度在 1×1 0 -7～ 3× 1 0 -6mol/L范围内呈线性关系 (r=0 .9988)。用该法测定了三黄片中黄芩甙的含量。该催化波是有机化合物极谱催化波的一种新类型—缔合 /平行催化波。IO-3 有双重作用 :( 1 )IO-3 作为配位体与吸附在电极表面的质子化黄芩甙形成离子对缔合物 ,引起峰电位的负移 ;( 2 )IO-3 及其还原中间体作为氧化剂氧化黄芩甙羰基经单电子单质子还原产生的自由基 。

In 0.24 mol/L Britton-Robinson buffer (pH 2.0) - 8 x 10(-3) mol/L KIO3 supporting electrolyte, baicalin yields a polarographic catalytic wave with peak potential - 1.20 V ( vs. SCE). First order derivative peak current is proportional to baicalin concentration in the range of 1 x 10(-7) similar to 3 x 10(-6) mol/L ( r = 0.9988). Baicalin content in pharmaceutical preparation Sanhuang tablets was determined by the catalytic wave. The catalytic wave of baicalin in the presence of KIO3 was suggested to be a parallel catalytic wave of ion-pair association complex as a new class of catalytic wave of organic compound. Here iodate anion as ligand formed an ion-pair association complex with protonated baicalin adsorbed at electrode surface, and it and its reduction species as oxidant oxidized the carbonyl radical of baicalin as catalyst in 1 e, 1H(+) reduction.