The effect of co-solvent in supercritical CO2 extraction

Using co-solvent

The research of supercritical CO2 extraction process using co-solvent, the equipment required for supercritical fluid extraction with CO2 as a single medium and the process parameters required for research are necessary in supercritical extraction using co-solvent.

The difference is that the device adds an co-solvent addition system.

Supercritical co2 extraction of rosemary essential oil using an entrainer

When optimizing the operating parameters, it is necessary to consider the type, addition method, amount and speed of co-solvent addition to the target substance extraction rate (or recovery rate) and selectivity influences.


Taking the extraction of effective components from andrographis paniculata as an example to illustrate the advantages of supercritical CO2 extraction using an co-solvent.

Studies have shown that andrographolide and dehydroandrographolide are the effective components in andrographolide, both of which are diterpene lactones.

However, andrographolide and dehydrated andrographolide are unstable under heat and are easily damaged during the traditional alcohol extraction pharmaceutical process.

At present, a new supercritical CO2 extraction process developed in China solves the problems of thermal decomposition and long production cycle of active ingredients during traditional process extraction and baking.


The following table compares the effects of different extraction methods on andrographis paniculata.

Supercritical pure CO2 extraction has the lowest yield, only 1/10 of other extraction methods; when using 95% ethanol as an co-solvent, operate according to optimized process conditions (extraction pressure 25MPa, extraction temperature 40 ° C, extraction time At 4h, the amount of co-solvent is 1/2 of the raw material), the rate of extracting andrographolide (8.3%), the content of andrographolide (19.79%), and the content of dehydrated andrographolide (12.27%) are much higher than the traditional extraction method, and the product quality is stable and the drug effect is high, and all the indicators are better than the original solvent method.

Although the ultrasonic ethanol extraction method and cold extraction with ethanol have better extraction results, the amount of solvent treatment is large and the solvent loss is large.

Extraction methodExtraction rate /%Andrographolide content /%Dehydrated andrographolide content /%
Cold ethanol6.1515.724.35
Ultrasonic ethanol extraction5.0510.173.43
Effect of different extraction methods on andrographis paniculata


The SCCO2 extraction process using co-solvents can broaden the application range of supercritical extraction, especially when the extracted components have little solubility in supercritical solvents or require highly selective extraction.

The SFE process using an co-solvent not only improves the solvent’s ability to extract solutes and reduces the amount of solvent required, but also greatly reduces the required pressure.

However, the disadvantage is that the co-solvent complicates the separation of the solute from the solvent and requires the addition of a special recovery system, such as the use of operation units such as evaporation and rectification.It is far less simple than using a single SCF process. The advantages and disadvantages of the method are determined.