Electrokinetic Chromatography‐based Micro Methods for Separation and Physiochemical Characterization of Very Hydrophobic Pharmaceuticals

This study established an efficient separation of the highly hydrophobic analytes fenofibrate, orlistat, lumefantrine and a micelle marker using microemulsion electrokinetic capillary chromatography. A starting buffer with sodium dodecyl sulphate, heptane and butan-1-ol resulted in a partial separation of the analytes. Various experimental parameters were investigated, including voltage, sample loading time, buffer composition and temperature. An excellent separation was achieved, and compounds with hydrophobicity of up to a calculated log P of 10.2 (est. 12) could be clearly distinguished. Due to observed variabilities in retention time when changing the capillaries, it is advisable to calibrate with a standard mixture before each measurement series.