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Significance and Conditions of Selection of Supercritical Extraction Medium

Supercritical CO2 Extraction Machine

Supercritical CO2 Extraction process is a powerful technique employed to extract valuable compounds from various materials. The choice of extraction medium, often referred to as the supercritical fluid, significantly influences the efficiency and selectivity of the extraction process.

Significance of Extraction Medium in Supercritical fluid extraction

The extraction medium used in SFE serves as the carrier for transporting the target compounds from the sample matrix to the collection vessel. The selection of the extraction medium is crucial due to its impact on extraction efficiency, selectivity, and the overall quality of the extracted compounds.

  1. Solubility and Selectivity: The extraction medium’s solubility for the target compounds plays a vital role in their extraction. A suitable extraction medium should exhibit high solubility for the compounds of interest while sparingly dissolving unwanted matrix components. This selectivity ensures the purity of the extracted compounds.
  2. Tunable Properties: Supercritical fluids can be fine-tuned by adjusting temperature and pressure to achieve desired extraction conditions. The extraction medium’s critical temperature and pressure should match the compounds’ characteristics, enabling optimal extraction while preventing degradation.
  3. Environmental Impact: The choice of extraction medium impacts the environmental footprint of the extraction process. Supercritical fluids are often chosen for their low environmental impact and ability to be easily separated from the extracted compounds.
  4. Ease of Removal: After extraction, the extraction medium should be separable from the extracted compounds without leaving traces or residues. This ensures the purity and safety of the final product.

Essential Conditions for Successful supercritical fluid extraction process

  1. Temperature and Pressure: The extraction medium must be above its critical temperature and pressure to exhibit supercritical properties. These conditions enable the extraction medium to simultaneously possess gas-like diffusivity and liquid-like solvating power, enhancing compound transport.
  2. Compatibility with Sample Matrix: The extraction medium should be compatible with the sample matrix. It should not react with the matrix components or cause any undesirable interactions that could affect the quality of the extracted compounds.
  3. Collection Conditions: The collection conditions, including temperature and pressure, should be optimized to ensure the extracted compounds remain stable. The solubility of the compounds in the extraction medium decreases as pressure decreases, facilitating their precipitation and collection.
  4. Safety Considerations: Supercritical conditions can be hazardous. Proper safety measures, such as pressure relief systems and temperature controls, should be in place to prevent accidents during the extraction process.

The choice of extraction medium should meet eight conditions

In supercritical fluid extraction, the selection of extraction medium is very important, and eight conditions should be met.

  1. Stable chemical properties, no corrosion to equipment,
  2. It has good selectivity to the extracted substances, and it is easy to obtain relatively pure products.
  3. The solubility of the extracted substance is high, so as to reduce the circulation amount of the solvent.
  4. The operating temperature should be lower than the decomposition temperature of the extracted substance.
  5. The critical temperature should be close to room temperature or operating temperature, neither too high nor too low.
  6. The critical pressure is low to reduce the compression power.
  7. Sufficient supply and low price.
  8. When used in medicine and food, it should be non-toxic.


In the realm of supercritical fluid extraction, the selection of the extraction medium is a critical decision that profoundly influences the success of the extraction process. The extraction medium’s solubility, tunable properties, and environmental impact all contribute to its significance. Furthermore, meeting essential conditions such as temperature, pressure, compatibility with the sample matrix, and safety considerations are paramount for ensuring successful extractions. By carefully considering the type of compounds, application requirements, and the advantages and disadvantages of various extraction media, researchers and engineers can harness the potential of supercritical fluid extraction to efficiently and selectively extract valuable compounds for a multitude of industries.