流动注射双安培法测定水飞蓟素

Flow Injection Biamperometric Determination of Silymarin

使用一支经恒电位预阳极化处理的双铂电极，在外加电位差为0，2V时，通过偶合水飞蓟素在一支电极上的氧化和氧化铂在另一支电极上的还原两个不可逆电极过程，在此基础上并结合流动注射技术提出了流动注射双安培法直接测定水飞蓟素的方法。在pH5．02B-R缓冲溶液中，水飞蓟素氧化峰电流与其浓度在4．0×10^-5～8．0×10^-4mol·L^-1范围内呈线性关系，检出限（3S／N）为2．0×10^-5mol·L^-1。连续20次测定1．0×10^-4mol·L^-1水飞蓟素标准溶液，所得相对标准偏差为3．3％。方法用于益肝灵片中水飞蓟素含量的测定，回收率为99．0％。

Under the conditions of applying the external potentials onto the pretreated binary Pt-eleetrodes having a potential difference △E of 0. 2 V, and coupling the 2 irreversible electrode processes of the oxidation of silymarin at one of the Pt electrode and the reduction at the other Pt-electrode which is coated with PtO through the anodization treatment, linear relationship between values of peak current Iv and concentration of silymarin was obtained in the range of 4.0×10^-5～8.0×10^-4mol·L^-1. Based on these facts and by applying the flow-injection technique, a method of direct FI-biamperometric determination of silyrnarin was proposed. The reaction was carried out in a B-R buffer medium of pH 5.02, and the detection limit （3S/N） of the method found was 2.0×10^-5mol·L^-1. Precision was tested at the concentration level of 1.0×10^-4mol·L^-1 of silymarin for 20 determinations, giving the value of RSD 3. 3%. The proposed method was applied to the analysis of a silyrnarin-containing drug, giving value of recovery of silymarin 99. 0%.