Supercritical Fluid Chromatography (SFC) is a chromatography technique with a lot of promise, but it has yet to gain popularity. ‘Much of what you normally can’t separate with LC, you can separate with SFC.’

‘Supercritical fluid chromatography (SFC, ed.) and ‘ordinary’ fluid chromatography (LC, ed.) have a lot in common, but the big difference is the composition of the mobile phase,’ says Lucie Nováková, professor in analytical chemistry at the Faculty of Pharmacy in Hradec Králové, Charles University in the Czech Republic. SFC has been around since the 1960s, but has gained renewed interest in recent years.

In SFC, the mobile phase consists of supercritical carbon dioxide. When you apply high pressure and the right temperature to CO2, the separation between the liquid and gas phase disappears. ‘But elution with supercritical CO2 is quite limited’, Nováková continues. ‘That is why you add an amount of organic component, usually methanol or ethanol when it comes to cosmetics. The consequence is that you don’t work supercritically, but subcritically, but you keep the favourable properties.’