Determination of allopurinol and its active metabolite oxypurinol by capillary electrophoresis with end-column amperometric detection

A simple method was proposed for the separation of allopurinol (AP) and its active metabolite oxypurinol (OP) by capillary electrophoresis with end-column amperometric detection. A running buffer composed of 15 mM Na2HPO4/NaH2PO4 at a pH 9.55, electrokinetic injection 7 s at 5 kV, separation voltage at 15 kV and detection potential at 1.20 V were investigated to be the optimal condition for the separation. The method exhibited low detection limit (S/N=3) as 1×10-8 mol/l for AP and OP, wide linearity range of 2×10-7 to 1×10-4 mol/l, 1×10-7 to 1×10-4 and high efficiency of 1.2×105 and 1.8 ×105 N/m for AP and OP, respectively. The potential application examined for the method was the determination of the spiked urine sample, which was proved to be sensitive and efficient.