Determination of synthetic pharmaceuticals in phytotherapeutics by capillary zone electrophoresis with contactless conductivity detection (CZE-C4D)

In this work, a method for simultaneous determination of amfepramone, fenproporex, sibutramine and fluoxetine was developed by capillary zone electrophoresis with capacitively coupled contactless conductivity detection (C4D) using a homemade capillary electrophoretic system. The optimized conditions for the separation of the pharmaceuticals by CZE were as follows: 50 mmol L− 1 phosphate buffer (pH 5.0) in 50/50 (v/v) mixture of water/acetonitrile as the working electrolyte, 15 kV separation voltage, 25 °C separation temperature, hydrodynamic injection by gravity using 20 cm injection height and 60 s injection time. The detection by C4D was carried out by using a homemade detector, which employs a sinusoidal wave generator operating at 600 kHz frequency and 2 Vpp wave amplitude. The optimized and validated CZE-C4D method was applied for the determination of the studied pharmaceuticals as adulterants in phytotherapeutic formulations commercialized in Brazil for slimming purposes.