Flow Injection Biamperometric Determination of Silymarin

Under the conditions of applying the external potentials onto the pretreated binary Pt-electrodes having a potential difference ΔE 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 Ip 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 silymarin 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 silymarin-containing drug,giving value of recovery of silymarin 99.0%.