Enantiospecific assay of citadiol--a key intermediate of escitalopram by liquid chromatography on Chiralpak AD-H column connected with UV and polarimetric detectors in series

A simple, rapid, selective and reproducible LC method for separation and quantitative determination of citadiol (CTD), a key intermediate of escitalopram has been developed. An optimum resolution > 3.0 was achieved on Chiralpak AD-H (250 mm x 4.6 mm); 5 microm column connected with UV and polarimetric detectors in series. The effects of organic modifiers, viz., methanol, ethanol, n-propanol and 2-propanol on enantioselectivity were evaluated. The limits of detection (LOD) and quantification (LOQ) were 0.02 microg/ml, 0.03 microg/ml and 0.07 microg/ml, 0.10 microg/ml for R-CTD and S-CTD enantiomers, respectively. The linearity of the method was studied in the range of 0.07-300 microg/ml and 0.1-300 microg/ml for R-CTD and S-CTD, respectively and the r2 was > or = 0.9999. The inter- and intra-day assay precision was less than 0.74% (%R.S.D.) and the recoveries were in the range 99.68-100.72% with %R.S.D. < 0.49%.