甘草苷的电化学伏安行为及其应用

目的: 研究了甘草苷(LQ)在碳糊电极(CPE)上的电化学行为及电化学动力学性质,据此建立了LQ的方波伏安法的新测定方法。 方法: 采用循环伏安法(CV)、控制电位电解库仑法(BE) 、计时库仑法(CC)、计时电流法(CA)及方波伏安法(SWV)等电化学方法。 结果: LQ在CPE上的电化学过程是一不可逆电化学氧化过程,氧化峰电位(E_p)为0.882 V。在扫描速度10~800 mV·s^-1范围内其氧化峰电流与扫描速度平方根(υ^1/2)呈良好的线性关系,表明LQ在CPE上的伏安行为是一受扩散控制的电极过程。用SWV法测定LQ的氧化峰电流与其浓度在1.8×10^-7~1.6×10^-3 mol·L^-1(r=0.9964)范围内呈良好的线性关系,检出限8.0×10^-8 mol·L^-1,RSD 2.8%~3.2%,加样回收率98.0%~102.0%。 结论: 该方法简便快捷,用于中成药及模拟尿样中LQ含量测定,结果令人满意。

Objective: To study electrochemical voltampere behaviors and its electrochemical kinetic parameters of liquiritin (LQ) at carbon paste electrode (CPE). Methods: Cyclic voltammetry (CV),bulk electrolysis with coulometry (BE),chronocoulometry (CC),chronoamperometry (CA) and square wave voltammetry (SWV). Results: Electrochemical behavior of LQ in 0.10 mol·L^-1PBS exhibits an irreversible electrochemical oxidation process at CPE,the oxidation peak potential (E_p) was 0.882 V.The plot of oxidation peak currents versus the square roots of the scanning rates in the potential range of 10-800 mV·s^-1 showed a straight line,as expected for a diffusion-limited electrochemical process.Electron transfer number n,electron transfer coefficient α,diffusion coefficient D and the apparent electrode reaction rate constant k_f were 2,0.54,8.69×10^-6 cm²·s^-1 and 1.27×10^-3 cm·s^-1,respectively.The changes of the oxidation peak currents with LQ concentration were examined by SWV.The oxidation peak currents versus LQ concentration have a good linear relationship in the concentration range of 1.8×10^-7-1.6×10^-3 mol·L^-1with the correlation coefficient of 0.9964,and the detection limit of 8.0×10^-8 mol·L^-1.The relative standard deviation was between 2.8%-3.2% and the recovery was in the range of 98.0%-102.0%. Conclusion: The proposed method is simple,accurate and can be used for the determination of LQ in samples with the satisfied results.