ANALYSIS OF FELODIPINE BY PACKED-COLUMN SUPERCRITICAL-FLUID CHROMATOGRAPHY WITH ELECTRON-CAPTURE AND ULTRAVIOLET ABSORBENCY DETECTION

A reproducible and selective supercritical fluid chromatography (SFC) method was developed for the analysis of felodipine, a drug indicated for the treatment of hypertension. Methanol-modified carbon dioxide wa s employed as the SFC mobile phase with both electron capture detectio n (ECD) and multi-wavelength detection (MWD) being used simultaneously for analyte determination. Chromatographic limit of detection (LOD) a nd limit of quantitation (LOQ), linear dynamic range (LDR) and injecti on precision were obtained in order to assess chromatographic and dete ctor performance for both the SFC/MWD and SFC/ECD/MWD systems. The met hod was shown to be stability indicating since felodipine could be sep arated from its potential oxidative degradation product, H152/37, in u nder 6 min (felodipine k' = 2.44). Sample throughput was increased by 60% with the SFC assay vs LC. The optimized SFC method was shown to be equivalent to an existing LC/UV procedure for the analysis of a susta ined-release tablet while realizing a 92% saving in disposable solvent waste. In order to achieve further solvent savings overall, supercrit ical fluid extraction (SFE) with 8% methanol-modified carbon dioxide a s the extraction fluid was used to extract felodipine from a sustained -release tablet (as opposed to traditional solvent extraction). Compar able drug recoveries were obtained with SFE sample preparation techniq ue when either SFC or LC extract analysis was utilized.