Abstract: A simultaneous detemination of rutin(RT) and L-ascorbic acid(Vc) in pharmaceutical preparations and fruit juices by capillary zone electrophoresis with electrochemical detection(CE-ED) was reported. The effects of potential of working electrode, concentration and pHof the running buffer, separation voltage and injection time on the CE-EDdetermination were investigated and discussed. RTand Vc could be well separated in a 25 mmol/Lborax-50 mmol/L NaH₂PO₄ buffer(pH8.0) with in 12 min. A 300 μm diameter carbon disc electrode was used as the working electrode positioned carefully opposite the outlet of the capillary in a wall-jet configuration at potential of 1.0 V(vs. SCE). There are excellent linearity between peak current and concentration of analytes in the concentration range of 1.0×10^-6—2.5×10^-4 mol/L for RT and 5.0×10^-6—2.5×10^-3 mol/Lfor Vc with the detection limits(S/N=3) of 8.0×10^-7 and 3.3×10^-6 mol/Lfor RTand Vc, respectively. Relative standard deviations(RSD) of the peak currents of RTand Vc were 2.85%(RT) and 1.65%(Vc) based on 9 determinations of the same sample containing 5.0×10^-5 mol/L RTand 2.5×10^-4 mol/L Vc. Recoveries of 97.94% for RT and 99.68% for Vc were obtained based on 5 determinations.

Key words: Capillary zone electrophoresis, Electrochemical detection, Rutin, L-Ascorbic acid