Articles
|
Supercritical fluid chromatography (SFC) is taking on new roles in the pharmaceutical industry. This technique resembles high-performance liquid chromatography (HPLC), but SFC uses CO2 as the mobile phase and needs less pressure across the columns. SFC is applicable from drug discovery through quality control.
“SFC is important for separation of chiral compounds,” says Martin Vollmer, product manager at Agilent Technologies (Santa Clara, Calif.), “and more and more drugs going to market are chiral compounds.” Where only one of a chiral compound’s enantiomers is the active form, pharmaceutical manufacturers must ensure that the other enantiomer does not trigger an adverse side effect. To distinguish characteristics of each enantiomer, researchers must first separate them.
SFC’s low solvent viscosity and superior diffusion characteristics lead to fast separations at moderate pressure. This speed makes SFC appealing even for separations of achiral compounds. “It can run very fast compared to standard liquid chromatography,” Vollmer says.
Agilent and Aurora SFC Systems (Redwood, Calif.) teamed up to make the Agilent 1260 Infinity Analytical Supercritical Fluid Chromatography System. Vollmer says that the “Fusion A5 module was developed by Aurora, and Agilent contributed the liquid chromatography part and sells the complete integrated system.” Vollmer adds that this system is 10-times more sensitive than other available SFC systems. It can also measure impurities in a sample that are only 0.05% of the main peak. “The Agilent SFC system achieves HPLC-like sensitivity due to the low noise in the detector, which is possible by superior CO2 conditioning in the A5 Fusion Module,” Vollmer says. The Fusion A5 module received an R&D 100 Award in 2010.
Making a transition from HPLC to Agilent’s SFC system should be pretty easy. “Anyone who is familiar with the Agilent liquid chromatography system can switch to Agilent’s SFC,” says Vollmer.
For scientists who own an Agilent 1100 or 1200 liquid chromatography system, Agilent now offers an SFC add-on option. “If they already have an Agilent LC system,” Vollmer says, “they can upgrade to SFC for less money than they’d pay for a completely new SFC system.”
Connecting columns
|
SFC’s lower pressure makes it possible to connect multiple columns in series. “Lately, we’ve even been seeing scientists coupling chiral with achiral columns to first separate enantiomers and then pull out any co-eluting impurities,” says Kari Carlson, brand manager at Phenomenex (Torrance, Calif.). “The low pressure of SFC provides flexibility so researchers can get creative with methods.”
Carlson sees many SFC users switching to Phenomenex’s Kinetex 2.6 ?m core-shell LC particle columns. She says that the new particle morphology provides “two to three times the efficiency of fully porous media, which presents exciting new opportunities in SFC.” These columns allow scientists to “couple up to a meter of columns for new levels of efficiency with an acceptable pressure drop.” She adds, “This way, you can get the column length you need when trying to pull similar compounds apart.”
Given such adaptability, SFC can be used in many ways. “All big pharmas employ SFC to some extent,” Carlson says, “and the technique is moving into quality control and quality assurance environments as methods are being validated in SFC mode.”
To move to SFC, though, Carlson expects relatively easy transitions for new users. One of the limiting factors to general adoption is the shortage of compelling SFC columns. In areas such as chiral chromatography, according to Carlson, the technique is already widely accepted thanks to the availability of SFC compatible columns, such as polysaccharide-based Lux chiral line. For achiral work, Carlson says, the recent interest and acceptance of core-shell particle technology is causing scientists to take a new look at SFC.
About the Author
Mike May is a publishing consultant for science and technology based in Austin, Texas.
