SFC intro to the interview

Frank van Geel, Chromedia, Netherlands

Abstract SFC works in principle the same as LC, and can be applied with the same parameters as with regular liquids such as pressure, temperature, and composition (gradients). The major difference is the solvent: CO2. The CO2 is in this application not a gas or liquid, but is in the so-called supercritical fluid phase brought about by the right pressure and temperature. The CO2 then has characteristics of both gas and liquid. A great advantage of SFC is, in addition to the fact that CO2 is friendlier to the environment than an organic solvents as Acetonitrile, and that the separation can be done much faster. The disadvantage is that the reaction conditions are not very transparent, and much knowledge and experience is needed in order to establish a good analysis. Log in to read more ....

Level

What is SFC?

History
In the 1980s SFC started with high expectations, it would compete – and maybe even replace - both GC and LC: the capillary SFC (columns in the order of ten micrometres), the very long columns separation would improve compared to GC analyses. Unfortunately there were many practical problems, in particular sample introduction and congestion of the column which made SFC a very unpractical technique. For the packed columns this is different. It would compete with LC. SFC disappointed there also: it appeared slightly faster and gave somewhat better separations, but together with the complex parameter settings not enough to replace LC, and many left disappointed the SFC technology. And in the same period, mass spectrometry developed so quickly that no extremely good separation was necessary to make a good analysis. SFC continued to exist in the shade, in specific applications e.g. chiral separations in Pharma.

Why the revival?
Now more experienced instrument companies as Waters, Agilent have entered the SFC market. They see a market in applications in pharma, in particular preparative, but also in the food lie opportunities. The Green environment-friendly concept, lower costs and the desire of suppliers to grow market share in the currently fragmented-LC market appear the reason for these incentives. It seems that SFC is increasingly integrated in the LC equipment and the software, so that step-by-step LC methods can be compared and maybe replaced by SFC.

Next: Interview with the experts.