Determination of testosterone/epitestosterone concentration ratio in human urine by capillary electrophoresis

A novel method for determining the testosterone/epitestosterone concentration ratio in human urine was established by capillary electrophoresis with diode-array detector. The urine samples were firstly purified by the solid extraction. The optimal experimental conditions were: running buffer pH = 4.74, 15.0 mmol L^-1 HAc-NaAc, separation voltage 25 kV, temperature 25 °C, sample injection pressure 3.43 × 10³ Pa, and duration 10 s. The testosterone and epitestosterone linear range were determined as 8.0-960.0 ng mL^-1, respectively. The testosterone and epitestosterone detection limits were determined as 4.6 and 4.5 ng mL^-1, respectively. The relative standard deviation was less than 0.36%.