The effect of the chiral compounds is the key factor in the pharmaceutical industry, and in order to evaluate the enantiomer, the chiral separation is taken up as a main theme. As a solution, Supercritical Fluid Chromatography (SFC) is drawing attention from many researchers. Since the separation capacity of SFC is higher than the one of HPLC, the SFC is powerful tool for separating the chiral compounds which is hard to separate by using HPLC.
The physical characteristics exhibited by supercritical fluid include a diffusion coefficient of dissolved molecules that is a hundred times greater than it is in liquid and a viscosity that is at least one digit smaller. A SFC system, which employs such a medium as a mobile phase, can be expected to serve as a separation analysis method that can rapidly perform separation without any degradation in separation efficiency, even at fast flow rates, due to a rapid mass transfer inside the column when compared with high-speed liquid chromatography that uses liquid as the mobile phase.
The Semi-Prep SFC and the Prep SFC system are applied to separation and purification with high recovery. When carbon dioxide is used as the medium, gasification will occur simply by keeping the separated and fractionated sample at an atmospheric pressure, making this one of the techniques capable of highly efficient refining with few post-processing hassles, such as elimination solvents after preparative isolation. This offers a host of advantages, including cost cuts related to the expense of purchasing solvents and discarding organic solvents among other things.
Supercritical Fluid Extraction (SFE) Systems
Supercritical Fluid Extraction (SFE) employs a supercritical fluid, most commonly CO2, as the A mobile phase solvent for the extraction. The intrinsic low viscosity and high diffusivity of supercritical CO2 has rendered SFE a faster extraction and higher efficiency technique when compared to traditional liquid extraction. This provides faster flow rates and thus faster extraction times without the requirement for a higher pressure system. The addition of a co-solvent to the CO2 flow can help tune the strength further. The extraction oven can offer temperatures up to 100°C. Lastly after the extraction vessel is the back pressure regulator, which provides the back pressure requirement to keep the CO2 supercritical, and is an integral part of the performance of the extraction.
JASCO offers a wide range of detectors with high pressure cells UV, Diode Array (real time collection of 3D spectra and chromatogram) and the only CD detector available for SFC. In particular, JASCO unique CD detector measures optical isomers with circular dichromatic absorption, and can measure both CD and UV chromatograms as well as g-factor (CD/UV) chromatograms. Since g-factor in particular has a proportional relationship with the compositional ratio of optical isomer sample, the CD detector can perform compositional measurements and high purity fractionation for non-separated peaks.
Before separating and collecting the target chiral compound, finding the optimum separation condition is required (column, solvent, etc.). In order to create the measurement conditions and measure the samples automatically, JASCO can offer the SFC screening for method development, which has the benefits of laborsaving and operation improvement.
By shortening the sample injection interval to let chromatograms overlap, the separation in prep mode can be done efficiency. It means that the separation and purification of even a large amount of sample can be carried out with high recovery and high purity in short time.
In the SFC using CO2 as mobile phase, it is one of main problems when collecting eluted sample that the separated sample is flown apart due to volume expansion (approx. 500 times) of released CO2. In order to improve the collection rate, JASCO has developed a Micro Cyclone Separator (MCS) for Semi-Prep SFC system, and a dedicated fraction collector Prep SFC system.