How Supercritical Fluid Extraction Works


Problem: Extraction of oils and flavors from natural products is traditionally accomplished with either organic solvents or by steam distillation. Both of these methods have significant drawbacks. Organic solvent extraction can leave trace amounts of the solvent in the extract. Many of these solvents are toxic or carcinogenic and disposing of waste solvent can be a significant cost. Additionally, some solvents are highly flammable, making their use in the process a potential hazard.

Steam distillation offers the advantage of using non-toxic water vapor to perform the extraction. However, the high temperatures required often thermally degrade the extract, changing its physical characteristics. When this happens, the flavor and fragrance of the extract is not the same as in the raw material. Oftentimes, yields from steam distillation are not as high as desired.

The SFT-2000 Supercritical Fluid Extractor

The Solution: High pressure carbon dioxide may be used in place of many traditional organic solvents and steam distillation. Above 1100 psi and 31.7ºC, carbon dioxide is in what is known as the “supercritical region.” Under these conditions, it has the solvating power of a liquid and the diffusivity of a gas. In short, it has properties of both a gas and a liquid. As a supercritical fluid, carbon dioxide is a superior solvent for the extraction of a wide variety of natural products.

A powerful characteristic of supercritical fluid extraction (SFE) is the ability to precisely control which component(s) of a complex matrix are extracted and which ones are left behind. This is accomplished through precise control of several key parameters such a temperature, pressure, flow rates and processing time.

Supercritical Fluid Technologies has developed the SFT-2000 Supercritical Fluid Extractor for performing easy, reproducible extractions in supercritical CO2. It can be configured with hand-tight vessels ranging from 100 ml to 5 liters, and it is easy to switch from one vessel to another. The instrument’s integrated fluid pre-heater ensures a consistent fluid temperature inside the extraction vessel, which is essential for reproducible results.

The SFT-2000 may be used to extract a wide variety of materials (such as, but not limited to, saw palmetto, ginseng, St. Johns wort, kava kava, gingko biloba, hops extraction/concentration, caffeine, glycosylated flavanoids, capcasin and paprika from chile peppers, mint oils, calmus root, valeria, garlic, catnip, nicotine, jasmine flower fragrance, Lanolin from wool, and Spruce needles). While the SFT-2000 can operate up to 200oC, the vast majority of extractions can be done under 60°C. At these benign temperatures, thermal degradation of products is not a concern. Since CO2 returns to its gaseous state upon exiting the extractor, there is no need to remove solvent from the product. Additionally, CO2 is nontoxic, so trace residue is never an issue with maintaining product integrity.

Yields are greater and product purity is higher with supercritical fluid extraction, as opposed to extractions performed by traditional techniques. Decomposition of materials almost never occurs due to the relatively mild processing temperatures, and there are no toxic residues.

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Categories: How it Works

Published In

Next-Generation Laboratories Magazine Issue Cover
Next-Generation Laboratories

Published: February 1, 2009

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Next-Generation Laboratories

New open-plan labs are meeting the need for more customized lab settings, including the ability to modify bench setup and support areas as needs change and increase interaction among researchers–now seen as preconditions for scientific breakthroughs.