Determination of diclofenac sodium by capillary zone electrophoresis with electrochemical detection

Abstract

Capillary zone electrophoresis was employed for the determination of diclofenac sodium using an end-column amperometric detection with a carbon fiber microelectrode, at a constant potential of 0.83 V vs. saturated calomel electrode. The optimum conditions of separation and detection are 4.90·10 −3 mol/l Na 2HPO 4–3.10·10 −3 mol/l NaH 2PO 4 (pH 7.0) for the buffer solution, 10 kV for the separation voltage, 5 kV and 10 s for the injection voltage and the injection time, respectively. The limit of detection is 2.5·10 −6 mol/l or 5.2 fmol ( S/ N=2). The relative standard deviation is 0.8% for the migration time and 4.7% for the electrophoretic peak current. The method was applied to the determination of diclofenac sodium in human urine.