Supercritical fluid chromatography
Encyclopedia
Supercritical Fluid Chromatography (SFC) is a form of normal phase chromatography that is used for the analysis and purification of low to moderate molecular weight, thermally labile molecules. It can also be used for the separation of chiral
compounds. Principles are similar to those of high performance liquid chromatography
(HPLC), however SFC typically utilizes carbon dioxide
as the mobile phase; therefore the entire chromatographic flow path must be pressurized.
molecules, and uses the same columns as standard HPLC systems. SFC is now commonly used for achiral separations and purifications in the pharmaceutical industry.
but fraction collection is more convenient because the primary mobile phase evaporates leaving only the analyte and a small volume of polar co-solvent.
Similar to an HPLC system, SFC can use a variety of detection methods including UV
/VIS, mass spectrometry
, FID
(unlike HPLC) and evaporative light scattering.
, however modifiers are added which can be used to change the chromatography, these are typically alcohols like methanol, ethanol
or isopropyl
. Other solvent such as acetonitrile
and chloroform can be used as modifiers. The solvent limitations are system and column based.
Chirality (chemistry)
A chiral molecule is a type of molecule that lacks an internal plane of symmetry and thus has a non-superimposable mirror image. The feature that is most often the cause of chirality in molecules is the presence of an asymmetric carbon atom....
compounds. Principles are similar to those of high performance liquid chromatography
High performance liquid chromatography
High-performance liquid chromatography , HPLC, is a chromatographic technique that can separate a mixture of compounds and is used in biochemistry and analytical chemistry to identify, quantify and purify the individual components of the mixture.HPLC typically utilizes different types of stationary...
(HPLC), however SFC typically utilizes carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
as the mobile phase; therefore the entire chromatographic flow path must be pressurized.
Applications
SFC finds use in industry primarily for separation of chiralChirality (chemistry)
A chiral molecule is a type of molecule that lacks an internal plane of symmetry and thus has a non-superimposable mirror image. The feature that is most often the cause of chirality in molecules is the presence of an asymmetric carbon atom....
molecules, and uses the same columns as standard HPLC systems. SFC is now commonly used for achiral separations and purifications in the pharmaceutical industry.
Apparatus
SFC utilizes carbon dioxide pumps that require that the incoming CO2 and pump heads be kept cold in order to maintain the carbon dioxide in a liquid state where it can be effectively metered at some specified flow rate. The chemist uses software to set mobile phase flow rate, co-solvent composition, and column temperature. In addition, SFC provides an additional control parameter - pressure - by using an automated back pressure regulator. From an operational standpoint, SFC is as simple and robust as HPLCHigh performance liquid chromatography
High-performance liquid chromatography , HPLC, is a chromatographic technique that can separate a mixture of compounds and is used in biochemistry and analytical chemistry to identify, quantify and purify the individual components of the mixture.HPLC typically utilizes different types of stationary...
but fraction collection is more convenient because the primary mobile phase evaporates leaving only the analyte and a small volume of polar co-solvent.
Similar to an HPLC system, SFC can use a variety of detection methods including UV
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
/VIS, mass spectrometry
Mass spectrometry
Mass spectrometry is an analytical technique that measures the mass-to-charge ratio of charged particles.It is used for determining masses of particles, for determining the elemental composition of a sample or molecule, and for elucidating the chemical structures of molecules, such as peptides and...
, FID
Flame ionization detector
A flame ionization detector is a type of gas detector used in gas chromatography. The first flame ionization detector was developed in 1957 by scientists working for the CSIRO in Melbourne, Australia....
(unlike HPLC) and evaporative light scattering.
Sample preparation
Any molecule that will dissolve in methanol or a less polar solvent can be analyzed using SFC, including polar solutes.[Ref needed]Mobile phase
The mobile phase is composed of high pressure liquid or supercritical carbon dioxideSupercritical carbon dioxide
Supercritical carbon dioxide is a fluid state of carbon dioxide where it is held at or above its critical temperature and critical pressure.Carbon dioxide usually behaves as a gas in air at STP or as a solid called dry ice when frozen...
, however modifiers are added which can be used to change the chromatography, these are typically alcohols like methanol, ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
or isopropyl
Isopropyl alcohol
Isopropyl alcohol is a common name for a chemical compound with the molecular formula C3H8O. It is a colorless, flammable chemical compound with a strong odor...
. Other solvent such as acetonitrile
Acetonitrile
Acetonitrile is the chemical compound with formula . This colourless liquid is the simplest organic nitrile. It is produced mainly as a byproduct of acrylonitrile manufacture...
and chloroform can be used as modifiers. The solvent limitations are system and column based.