title: Development and validation of a capillary electrophoresis method for the simultaneous determination of impurities of escitalopram including the R-enantiomer.
abstract: A stereospecific capillary electrophoresis assay for the simultaneous determination of related substances and the enantiomeric purity of escitalopram was developed by a central composite face-centered factorial design and subsequently validated. Separations were carried out in a 50 microm, 47/40 cm fused-silica capillary. The optimized conditions included 20mM phosphate buffer, pH 2.5, containing 0.5mg/ml beta-cyclodextrin and 22 mg/ml sulfated beta-cyclodextrin as background electrolyte, an applied voltage of -20 kV and a temperature of 28 degrees C. Salicylic acid was used as internal standard. The assay was validated for the (R)-enantiomer of citalopram and the enantiomers of the impurity citadiol in the range of 2.5-150 microg/ml and 2.5-50 microg/ml, respectively. The limit of detection was 0.02% for all compounds, the limit of quantitation 0.05%, relative to a concentration of escitalopram of 5mg/ml. Intraday precision of migration time and peak area ratio were in the range of 0.17-0.44% and 1.64% and 6.25%, respectively. Relative standard deviations of interday precision ranged between 0.84% and 1.85% in the case of migration times and between 5.20% and 9.28% for peak area ratio. The assay was applied to the determination of the purity of escitalopram in bulk drug and tablets. (R)-Citalopram and (S)-citadiol were detected as impurities.
authors.affiliation: Department of Medicinal/Pharmaceutical Chemistry, School of Pharmacy, University of Jena, Philosophenweg 14, 07743 Jena, Germany.
authors.forename: Bunleu
authors.initials: B
authors.lastname: Sungthong
authors.forename: Pavel
authors.initials: P
authors.lastname: Jác
authors.forename: Gerhard K E
authors.initials: GK
authors.lastname: Scriba
mesh_terms: D002021:Buffers; D015283:Citalopram / Q000032:analysis* / Q000737:chemistry; D004340:Drug Contamination; D019075:Electrophoresis, Capillary / Q000379:methods* / Q000592:standards; D006863:Hydrogen-Ion Concentration; D009570:Nitriles / Q000032:analysis; D015203:Reproducibility of Results; D017367:Selective Serotonin Reuptake Inhibitors / Q000032:analysis* / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry; D013237:Stereoisomerism; D013431:Sulfates / Q000737:chemistry; D013607:Tablets; D047392:beta-Cyclodextrins / Q000737:chemistry
chemical_list: D002021:Buffers; D015283:Citalopram; D009570:Nitriles; D017367:Selective Serotonin Reuptake Inhibitors; D012822:Silicon Dioxide; D013431:Sulfates; D013607:Tablets; D047392:beta-Cyclodextrins; C517833:citadiol