Capillary electrophoretic (CE) and high performance liquid chromatographic (HPLC) methods were developed and optimized for the determination of antazoline (ANT) and tetrahydrozoline (TET) in ophthalmic formulations. Optimum electrophoretic conditions were achieved using a background electrolyte of 20 mM phosphate buffer at pH 7.0, a capillary temperature of 25 °C, a separation voltage of 22 kV and a pressure injection of the sample at 50 mbar for 17 s. HPLC analysis was performed with Kinetex (150 × 4.6 mm ID × 5 μm) (Phenomenex, USA) analytical column with 1 mL min−1 flow rate of mobile phase which consisted of 0.05% TFA in bidistilled water (pH adjusted to 3.0 with 5 M NaOH) and acetonitrile/buffer in the ratio of 63:37 (v/v) at room temperature. Injection volume of the samples was 10 μL and the wavelength of the detector was set at 215 nm for monitoring both analytes.
Calibration graphs showed a good linearity with a coefficient of determination (R2) of at least 0.998 for both methods. Intraday and interday precision (expressed as RSD%) were lower than 2.8% for CE and 0.92% for HPLC. The developed methods were demonstrated to be simple and rapid for the determination of ANT and TET in ophthalmic solutions providing recoveries in the range between 97.9 and 102.70% for CE and HPLC.