Comparative study of different chemistries and particle properties, high‐performance liquid chromatography stationary phases in separation of escitalopram oxalate and its impurities in different pharmaceutical dosage forms

The liquid chromatographic separation performance of 12 different columns was evaluated for the estimation of the escitalopram oxalate and six of its impurities in different pharmaceutical formulations. All columns exhibited a reasonable separation power. Six columns with three different chemistries and two different particle morphology (i.e. core‐shell and fully porous particle) were nominated for further evaluation. The objectives of the current study were to develop a simple method for detection of escitalopram oxalate and its impurities and to compare the separation power of the stationary phase of different chemistry and particle properties. The separation was carried out under isocratic elution by using acetonitrile/methanol/water/phosphate buffer solution (pH = 3.5, 50 mM) (25:5:20:50, v/v/v/v) mixture as mobile phase, with a flow rate of 1.2 mL min−1. The core‐shell phenyl‐hexyl column showed the best separation performance over the traditional octadecyl and pentafluorophenyl phases. The developed method was applied for detection of escitalopram oxalate and its impurities in valid and expired dosage forms.