Analysis of mono-, di- and triglycerides in pharmaceutical excipients by capillary supercritical fluid chromatography

Mono-, di- and triglycerides are important components of oils, fats and other natural products. Since in general fatty acids are mixtures and glycerol can be differently substituted, finger-prints of the composition are suitable for better characterization. Since capillary supercritical fluid chromatography (SFC) employing carbon dioxide as mobile phase is compatible with flame ionization detection, it is possible to analyse many solutes at trace levels. Supercritical carbon dioxide offers higher solute diffusivity compared with the inert carrier gas conventionally used in gas chromatography and has a lower viscosity than the liquid solvents used in HPLC. Thus, glycerides of fatty acids can be separated and eluted at a lower temperature and with shorter analysis time in SFC. In this study the analysis of mono-, di- and triglyceride mixtures in several pharmaceutical excipients is reported using capillary SFC. Quantitative analysis is possible on the basis of a response factor established for each analyte. The accuracy of the method and its advantages are demonstrated.