Increasing concern about the quality, safety, usage, and disposal of hydrocarbon based solvents as well as stricter regulations on the residual levels of solvents have all contributed to many industries switching to SFE technology for the extraction, fractionation, and isolation of chemical compounds.

The biggest advantage of SFE is that it leaves no traces in the product. After extraction, the carbon dioxide is either depressurized and vented, or recycled for further extraction use. Any residual trace of carbon dioxide in the product dissipates into the atmosphere within a few hours.  As a tunable solvent, CO₂ is nontoxic, nonflammable, and physiologically compatible.

• Environmentally friendly
• Lower operating costs
• Little to no residual solvent
• Processes thermally labile compounds
• Safe
• Scalable

Waters preparative SFE systems come in a variety of sizes to meet your needs. The size of the main extraction vessel can be 100mL, 500mL, 1000mL, 2000mL, or 5000mL. The systems also offer many options.

System options include:

• Co-solvent pump, for extracting polar samples.
• CO₂ flow meter, to measure the amount of CO₂ being supplied to the system
• Multiple extraction vessels, to extract different sample sizes or to increase the throughput of the system
• Multiple fraction collectors, to fractionate the extract
• Recycle system, allowing the reuse of CO₂
• Rapid Expansion of Supercritical Solutions (RESS), for particle formation

Waters SFE systems extract chemical compounds using supercritical CO₂ instead of an organic solvent. The supercritical fluid state occurs when a fluid is above its critical temperature and critical pressure. This supercritical state allows CO₂ to take on properties of a gas (high diffusivity, low surface tension) as well as maintaining the solvating power of a liquid.

Manipulating the temperature and pressure of CO₂ alters the solvent power and allows the material of interest to be selectively extracted. The sample is placed in an extraction vessel and pressurized with CO₂ to extract the compound of interest. (As supercritical CO₂ will only extract non-polar compounds, a small percentage of co-solvent can be added to extract polar compounds.) This compound is then transferred from the extraction vessel to a fraction collector. The back pressure regulator located between these vessels allows for controlled depressurization of the compounds of interest and the CO₂. At the exit of the BPR, the system pressure is reduced to near atmospheric conditions causing the CO₂ to lose its solvating power and the extracted material precipitates out of solution into the fraction collector. The condensed CO₂, now a gas, is sent to vent or can be recycled.