Separation of six purine bases by capillary electrophoresis with electrochemical detection

Capillary zone electrophoresis with electrochemical detection (ED) has been employed for the separation and determination of adenine (A), guanine (G), theophylline (Thp), hypoxanthine (HX), xanthine (Xan) and uric acid (UA). Effects of several important factors such as the acidity and concentration of running buffer, separation voltage, injection time and detection potential were investigated to acquire the optimum conditions. The detection electrode was a 300 mum carbon disc electrode at a working potential of +0.95 V (versus saturated calomel electrode (SCE)). The six purine bases can be well separated within 14 min in a 40 cm length fused-silica capillary at a separation voltage of 10 kV in a 100 mmol/l borate buffer (1313, pH 10.0). The current response was linear over about three orders of magnitude with detection limits (S/N = 3) ranging from 0.157 x 10(-6) to 0.767 x 10(-6) mol/l for all compounds. The proposed method was successfully applied to determine Thp in tea and aminophylline tablets, UA in human urine, and two purine bases in DNA. (C) 2002 Elsevier Science B.V. All rights reserved.