Are mobile phases used in chiral separation using HPLC and SFC the same?
Because SFC uses carbon dioxide as the primary mobile phase (hence the supercritical nature of this technique) and small amounts of organic solvents (often ~ 15% or less) plus optional additives the answer would be no.
In general, SFC normal phase methods are far more restricted in mobile phase choice. You would be wise to read up on the fundamentals of liquid chromatography as well as supercritical fluid chromatography first to gain a basic level understanding of the concepts and methods used. This would assist you to understand the basic differences in the techniques. You will learn far more in life if you choose to put the time in to investigation such basic questions yourself first, before asking others on the web. Many great texts exist to teach you these concepts and your rewards will be the skills to research questions as well as the knowledge that you have discovered.
No. Chiral Chromatography requires a chiral mobile phase (or component most of the time) to ensure baseline separation.
No. The mobile phase must be in supercrirical state. But it don't have to be chiral.
regards
G
*Chiral chromatography does not "require" a chiral mobile phase. In fact most separations are performed on chiral stationary phases with ordinary solvents. Chiral mobile phase additives are much less common in HPLC and SFC methods (more commonly seen with chiral CE methods).
I stand corrected! I guess I remembering >20 year old technology (back in the 'dark' ages).
There are chiral columns that can work in both HPLC conditions and SFC conditions (although you need to marry a particular column to one condition and not switching back and forth). And for chiral HPLC you can have normal phase HPLC (mostly uses hexane/isopropanol/diethylamine mixtures) and reverse phase HPLC (mostly water/acetonitrile mixtures). But as people pointed out, the mobile phases are very different between HPLC and SFC.
"although you need to marry a particular column to one condition and not switching back and forth".
Sorry, that is not true. A column which has been correctly used for an SFC application can be used for a traditional HPLC use too (and vice-versa). As long as you properly clean it after each use and do not damage the surface chemistry, it will be fine (same as with other HPLC methods). We have tested many chiral column screening sets on both our SFC and HPLC systems with no changes measured between tests. Some chiral phases are very delicate so no matter which technique you use, you must be careful. As a general rule for all HPLC columns, if used with any strong acids, bases or ion-pairing additives, the columns should be labeled and dedicated for use only with that same additive. This is true for all HPLC columns, not just chiral columns. *The surface chemistry is changed after use with many of these compounds (esp. ion pairing compounds!). This may result in Rt changes and poor %RSD causing methods to fail testing and data being invalid.
It may change. In SFC CO2 is used as a nonpolar solvent so as a polar solvent methanol, acetonitrile and more solvent you can use as per column chemistry.
For experienced chromatographers using HPLC or SFC for chiral separations, here is a link to a free training article on the use of different alcohols in chiral method development. You may find the tips useful when developing methods.
- "CHIRAL HPLC / SFC METHOD DEVELOPMENT (Alcohols)"; April 1, 2011: https://hplctips.blogspot.com/2011/04/chiral-hplc-sfc-method-development.html