Determination of letrozole, anastrozole and exemestane by capillary zone electrophoresis

Abstract

A new validated capillary zone electrophoresis method was developed for the quantification of three aromatase inhibitors - anastrozole, letrozole and exemestane. After preliminary analysis a sodium tetraborate background electrolyte containing carboxymethyl β-cyclodextrine was selected for the simultaneous determination of the three aromatase inhibitors. 100 mM sodium tetraborate containing 5 mM carboxymethyl β- cyclodextrine as buffer addtive, 25 kV applied voltage, 20 mbar/2 s injection pressure and 25°C temperature were selected as optimum parameters for the determination. Analysis was performed in approximately 10 minutes. Validation parameters, including linearity, precision, detection and quantification limits were determined. Our results prove the applicability of capillary zone electrophoresis for the simultaneous determination of the three aromatase inhibitors from pharmaceutical products. The applicability of the optimized method was also tested for biological samples, proving its reliability for the determination of letrozole without any special treatment of the analyzed spiked urine sample and presenting potential for other biological matrices.