SFE Cartridge Column Preparations

Cartridge columns consist of 0.5-1 g of 40- m particles sandwiched between 30-jUm frits. The column s body may be a tube shrunk around a sandwich of bed support frits and packing. In another type, the frits and packing may be pushed into a small syringe barrel. The 0.5-g SFE has a sample capacity of about 25 mg and a void volume of about 1.5 mL. 

The SFE can also be used for extractions. Reverse-phase cartridges are available that, after activation with methanol, can be used to remove nonpolar materials from solution. This is true chromatography, not filtration. The adhering material can be eluted in step-gradient fashion with increasing nonpolar solvent fractions. Although they do not have the efficiency of an HPLC 

Although organic solvents may aid in making your compound soluble, be careful. Many polymeric ion exchangers will shrink in the presence of more 

Size separations are seldom run on SFE columns because the column beds are not long enough to give an effective size cut. The only exception to this is the use of desalting SFE columns containing Sephadex G-25 for removing salt in a buffer solution from a protein fractionation. 

Affinity SFE cartridges are coming on the market for antibody preparation (protein G and protein A columns), for hydrogenase preparations (blue, red, and green dye columns), and activated cartridges that can bind proteins and amino-containing compounds to prepare affinity columns for specific uses are available. These may go beyond the basic definition of the SFE, but they are just simply variations on the same theme. 

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