应用黄芩素测定食品中的痕量铝

Application of baicalein in the determination of trace aluminum in food

黄芩素在一定的电位范围内具有明显的电化学信号，Al3＋的加入对于黄芩素的电信号具有显著的抑制作用，且氧化峰电流的降低值△Ip与Al3＋浓度呈良好的线性关系，基于此建立了方波伏安法测定Al3＋的新方法。通过对支持电解质、黄芩素的浓度、加入顺序等条件进行优化，发现在2．0×10^-8一5．0×10^-7mol／L和5．0×10^-7一8．0×10^-6mol／L范围内，△IP与Al3＋浓度成正比，检出限为2．2×10^-8mol／L；并对油条中的Al3＋进行了检测。同时，利用循环伏安法、紫外光谱法等初步探讨了黄芩素与Al3＋的作用机理，研究发现黄芩素在玻碳电极上发生了2电子2质子的电化学转移行为，且其电极氧化过程受到吸附作用控制；加入Al3＋后，二者生成了一种新型络合物，导致黄芩素的电化学活性显著降低。

Aluminum had been recognized as a neurotoxin. It was controlled as contaminants in food by the world health organization and many countries. Baicalein had obvious electrochemical signals in the potential range. But the electrochemical signals of baicalein could be significantly inhibited with the addition of aluminum. And the reduction of oxidation peak current （ △Ip ） was linear with the concentration of Al3 ＋. Based on this, a new analytical method for the determination of trace aluminum was established with square wave voltammetry. The supporting electrolyte, concentration of baicalein, sequence of adding reagents were optimized. In the range of 2.0 ×10^-8 ~ 5×10^-7mol/L and 5.0 ×10^-7 - 8.0 ×10^-6 mol/L, the reduction of oxidation peak current （△Ip） was in proportion to the concentration of Al3＋. The detection limit of this method was 2. 2 ×10^-8 mol/L. Alumirmra in fried sticks was successfully detected by using this method. At the same time, the mechanism of baicalein and aluminium was preliminary studied by UV spectroscopy, cyclic voltammetry, and so on. It is found that baicalein had 2 electrons and 2 protons transfer behavior on a glassy carbon electrode. And the electrode oxidation process was controlled by adsorption. When the aluminum was added, they produced a new complex. It significantly fetch down the electrochemical activity of baicalein.