Determination of enantiomeric bioactives
using new analytical SFC instruments
Manuscripts dealing with the new analytical SFC devices and comparing analytical HPLC with analytical SFC for enantiomeric separations are reviewed. Supercritical fluid chromatography (SFC) has long been a common tool for preparative separation of enantiomers in science and industry, since it offers some major advantages over high performance liquid chromatography (HPLC). For example SFC allows for higher flow rates, shorter analysis and total run times and usage of longer columns resulting in higher resolution. Recently new SFC instruments became available for analytical application with major improvements in terms of back pressure regulation. This led to enormous progresses in robustness and analytical performance.
The use of supercritical fluids (SF) as mobile phase in chromatography was first realized in the 1960’s, at that time named high-pressure gas chromatography or dense gas chromatography (1–3) and chiral SFC separations were first reported in the mid 1980’s (4). The acceptance of SFC was initially hampered by technical realization which led to poor reproducibility and reliability (e.g. shifting retention times) (5–8). The polarity of SF strongly depends on pressure and temperature and thus the precise regulation of the back pressure was the most serious challenge in early SFC. SFC has thereby fulfilled a niche existence in chiral preparative chromatography as more economical alternative to normal phase (NP) HPLC (most chiral stationary phases perform best in NP-HPLC (9)). The physico-chemical properties of supercritical fluids as well as its thermodynamic description is availale from Guiochon and Tarafder (2).
Meanwhile guidelines of the American Food and Drug Administration (FDA) as well as of the European Medicines Agency (EMA) require stereoselective investigations of pharmakokinetic, pharmakodynamic, stability etc. propert ...