Determination of rutin and L-ascorbic acid in pharmaceutical preparations and fruit juices by capillary zone electrophoresis with electrochemical detection

A simultaneous determination of rutin(RT) and L-ascorbic acid(Vc) in pharma ceutical preparations and fruit juices by capillary zone electrophoresis wi th electrochemical detection(CE-ED) was reported, The effects of potential of working electrode, concentration and pH of the running buffer, separatio n voltage and injection time on the CE-ED determination were investigated a nd discussed. RT and Vc could be well separated in a 25 mmol/L borax-50 mmo l/L NaH2PO4 buffer(pH 8.0) within 12 min. A 300 mum diameter carbon disc el ectrode 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 concentra tion of analytes in the concentration range of 1.0 x 10(-6)-2.5 x 10(-4) mo l/L for RT and 5.0 x 10(-6)-2.5 x 10(-3) mol/L for Vc with the detection li mits (S/N = 3) of 8.0 x 10(-7) and 3.3 x 10(-6) mol/L for RT and Vc, respec tively. Relative standard deviations (RSD) of the peak currents of RT and V c were 2.85% (RT) and 1.65% (Vc) based on 9 determinations of the same samp le containing 5.0 x 10(-5) mol/L RT and 2.5 x 10(-4) mol/L Vc. Recoveries o f 97.94% for RT and 99.68% for Vc were obtained based on 5 determinations.