Determination of Escitalopram Oxalate and L-Methylfolate in Tablet by Spectrophotometric and Reverse Phase High-Performance Liquid Chromatographic Methods

Two new simple and selective assay methods have been presented for the analysis of Escitalopram Oxalate (ESC) and L-Methylfolate (L-MF) in pharmaceutical formulations. The ultraviolet (UV)-Spectrophotometric simultaneous equation method was based on the measurement of absorbance at 238 nm (ʎmax of ESC) and 284 nm (ʎmax of L-MF) in methanol. The assay was linear over the concentration ranges 0.5-12.0 μg/mL for ESC and 0.5-9.0 μg/mL for L-MF. The quantitation limits for ESC and L-MF were found to be 0.912 and 0.667 μg/mL; while the detection limits were 0.301 and 0.220 μg/mL for ESC and L-MF, respectively. The second method involved isocratic reversed-phase liquid chromatography using a mobile phase composed of methanol-0.02 M phosphate buffer (pH 5.5) (75:25, v/v), Hypersil BDS-C18 Column (5 µm, 250 mm × 4.6 mm i.d.) with detection at 270 nm. The linearity ranges were found to be 3.0-30.0 and 0.75-22.5 μg/mL for ESC and L-MF, respectively. The limits of detection were found to be 1.065 and 1.160 μg/mL for ESC and L-MF, respectively. The limits of quantitation were found to be 3.226 and 3.515 μg/mL for ESC and L-MF, respectively. The proposed methods were successfully applied to the determination of commercially available tablets with a high percentage of recovery, good accuracy and precision.