双通道-双工作电极毛细管电泳电化学法快速检测大黄酸

Fast determination of rhein by capillary electrophoresis with a dual-channel and dual-electrode electrochemical detection system

报道了一种测定大黄酸的快速毛细管电泳电化学方法。采用简易制作的一种双通道-双工作电极电化学系统,可以实现电导法和安培法同时检测;优化选择了缓冲介质、工作电极、检测电位、毛细管长度和内径以及分离电压等实验参数,并对提高分析速度进行了初步研究和探讨。结果表明:大黄酸在100s内可以得到较好的分离测定,电导法和安培法的线性范围分别为6.83×10-4～1.07×10-5mol/L和3.41×10-4～2.67×10-6mol/L,最小检出浓度分别为5.28×10-6mol/L和3.16×10-7mol/L。采用设计的双通道 双工作电极检测装置,可以充分发挥电导法和安培法的优越性,对样品峰及样品的纯度进行确证;另外通过采用较短的毛细管与适当提高分离电压,可以提高分析速度。该法已用于中药大黄中大黄酸的测定。

A new type of dual-channel and dual-electrode electrochemical detector of capillary electrophoresis was used for determination of rhein. Two detectors including amperometric and conductometric detector were connected to the same capillary electrophoresis system and simultaneously performed for detecting the same sample. The effects of some important factors, such as the detection potential, the concentration of the running buffer, separation voltage, the length and inner diameter of capillary on separation were investigated. Under the optimum conditions rhein was eluted in 100 seconds and the detection limits of two detectors were 5.28×10^(-6) and 3.16×10^(-7) mol/L, respectively. The response was linear in two and three orders of magnitude. The method was successfully applied to determine rhein in Chinese medicine with satisfactory results.