Extraction principle of aqueous two phase extraction technology

The principle of aqueous phase extraction: there is an intermolecular interaction force, and this intermolecular force increases with the increase of the relative molecular mass. When there is mutual repulsion between two polymers, because the repulsion between molecules with a larger relative molecular mass is dominant compared with the mixed entropy, that is, the same molecule will gather around a polymer molecule and repel different molecules, and when equilibrium is reached, two phases rich in different polymers are formed.

The principle of water extraction alcohol precipitation is: some macromolecules in the water extractHydrophilicImpurities are insoluble in a certain concentrationEthanol, add an appropriate amount of ethanol to the aqueous extract to remove the impurity precipitation.

The water extraction alcohol precipitation method (water alcohol method) refers to the addition of ethanol to the concentrated liquid of water extraction of traditional Chinese medicine to achieve different alcohol content, and the solubility of certain pharmaceutical components in the alcohol solution.

A method to reduce precipitation precipitation and refine the aqueous extract after solid-liquid separation.

Characteristics of alcohol precipitation method:

1. Alcohol precipitation is a method of removing impurities in the extract by ethanol precipitation. It removes impurities, reduces the dosage of medicine, achieves the characteristics of refining and convenient preparation, and makes the original Chinese medicine decoction made into Chinese patent medicine.

to be carried out; 2. The boiling point of ethanol is moderate (78).

After repeated use, it also has a bactericidal effect, and the materials treated with ethanol are not easy to mold and deteriorate;

3. For traditional Chinese medicine compounds with unclear pharmacodynamic ingredients and unclear mechanism of action, it is a simple and applicable extraction method.

However, there are certain limitations to the use of alcohol precipitation. For example, solid preparations should not be used, because polysaccharides are removed during alcohol precipitation, and several times the amount of starch and dextrin is added after the fermentation liquid **ethanol is concentrated.

and other excipients before they can be formed, which will increase the cost.

The principle of aqueous phase extraction: there is an intermolecular interaction force, which increases with the increase of the relative molecular mass. When there is mutual repulsion between two polymers, because the repulsion between molecules with a larger relative molecular mass is dominant compared with the mixed entropy, that is, the same molecule will gather around a polymer molecule and repel different molecules, and when equilibrium is reached, two phases rich in different polymers are formed.

Liquid-liquid extraction technology is one of the commonly used separation technologies in the chemical industry, and it is also widely used in biochemical industry. However, most of the biological substances are biologically viable and need to be separated and purified at low temperature or room temperature, which cannot be done by traditional extraction techniques. Considering this situation, aqueous phase extraction is a new type of liquid-liquid extraction separation technology developed based on the theory of liquid-liquid extraction and considering the maintenance of biological activity.

Compared with the traditional liquid-liquid separation method, the separation and purification of proteins by aqueous phase extraction technology has the following advantages: the water content of the system is high, which can reach more than 80%; Proteins are not easily denatured in it; The interfacial tension is much lower than that of the water-organic solvent two-phase system, which helps to strengthen the inter-phase mass transfer of the phase number school. The phase splitting time is short, generally only 5 15 min; It is easy to envy and envy, amplify and carry out continuous operation; The extraction environment is mild and the biocompatibility is high; Polymers have a stabilizing and protective effect on the structure of proteins, etc. Due to the many advantages of aqueous phase extraction technology, it has been widely used for the separation and purification of proteins, nucleic acids, amino acids, peptides, organelles and other products.

1 Principle of two-phase aqueous extraction.

Two-phase aqueous system refers to a two-phase or multi-phase aqueous system that is immiscible with each other or between polymers and inorganic salts after being dissolved in water at an appropriate concentration. The polymer-polymer-water system mainly relies on the incompatibility between polymers, that is, the spatial hindrance of polymer molecules, which promotes their phase separation. Polymer-salt-water systems are generally considered to be the result of salting out.

The principle of aqueous phase extraction is similar to that of aqueous phase extraction, which is based on the selective distribution of substances between the two phases, but the difference lies in the nature of the extraction system. When the biomass enters the two-aqueous phase system, the concentration in the upper and lower phases is different due to the surface properties, charge action, and the presence of various forces (such as hydrophobic bonds, hydrogen bonds, and ionic bonds, etc.) and the influence of the environment. The partition coefficient k is equal to the concentration ratio of biological substances in the two phases, and because the k values of the proteins are not the same (roughly between 011 and 10), the two-aqueous phase system has good selectivity for the partitioning of various proteins.

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What is the principle of the two-phase finch hall solvent extraction method?

a.The melting point of the substance is different.

b.The boiling point of the root bark is different.

c.It varies depending on the type of substance.

d.Depending on the substance, the partition ratio in the two-phase solvent is different.

Correct answer: d

The aqueous solution of some hydrophilic polymers can form two phases after exceeding a certain concentration, and the water accounts for a large proportion in both phases, that is, the formation of aqueous two-phase system (ATPS). In the late 50s of the 20th century, Albertsson developed the aqueous two-phase extraction method, also known as the aqueous phase partitioning method. In the 70s of the 20th century, scientists developed the application of aqueous phase extraction in the process of biological separation, which opened up a new way for the separation and purification of proteins, especially intracellular proteins.

Polymer incompatibility of two-phase aqueous extraction: According to the second law of thermodynamics, mixing is an entropy increase process that can be carried out spontaneously, but there is an intermolecular interaction force, and this intermolecular force increases with the increase of relative molecular weight. When there is mutual repulsion between two polymers, because the repulsion between molecules with a larger relative molecular mass is dominant compared with the mixed entropy, that is, the same molecule will gather around a polymer molecule and repel different molecules, and when equilibrium is reached, two phases rich in different polymers are formed.

This phenomenon of phasing in a solution containing polymer molecules is called insolubility of polymers.

There are many double polymer systems that can form dual aqueous phases, such as polyethylene glycol (PEG), dextran (DX), polypropylene glycol, polyethylene glycol, methylcellulose and dextran. The bipolymer system used in the aqueous two-phase extraction is PEG DX, where the upper phase is rich in PEG and the lower phase is rich in DX. In addition, the mixed solution of polymers and inorganic salts can also form a biqueous phase, for example, peg potassium phosphate (kpi), peg ammonium phosphate, peg sodium sulfate, etc. are often used for aqueous biqueous extraction.

The upper phase of the PEG inorganic salt system is rich in PEG and the lower phase is rich in inorganic salts.

The partition coefficient of biomolecules depends on the various interactions with solutes in the two-aqueous phase system, including electrostatic, hydrophobic and bioaffinity. Thus, the partition coefficient is the sum of various interactions.

Some polymer aqueous solutions (such as polyethylene glycol sulfate aqueous solution with molecular weight from thousands to tens of thousands) can be divided into two aqueous phases, and the solubility of proteins in the two aqueous phases is very different. Therefore, the aqueous two-phase extraction process can be used to separate water-soluble biological products such as proteins.

Advantages of dual aqueous phases.

As a new type of separation technology, ATPE has the following advantages for the extraction and purification of biological substances, natural products, antibiotics, etc.:

1) High water content (70 --90), extraction in a system close to the physiological environment, will not cause inactivation or denaturation of bioactive substances;

2) The required protein (or enzyme) can be extracted directly from the fermentation broth and culture medium containing the cellular, and the intracellular enzyme can be extracted directly without crushing, omitting steps such as crushing or filtration;

3) The phase separation time is short, and the natural phase separation time is generally 5 min 15 min;

4) The interfacial tension is small (10-7 10-4mn m), which facilitates the mass transfer between the two phases, and the contact angle formed by the interface and the test tube wall is almost a right angle;

5) There is no problem of organic solvent residue, and polymers are generally non-volatile substances and harmless to the human body;

6) A large number of impurities can be removed together with solid substances;

7) It is easy to scale up and operate continuously, and can be directly connected to the subsequent purification process without special treatment;

8) The operating conditions are mild, and the whole operation process is carried out at room temperature and pressure;

9) Affinity aqueous phase extraction technology can improve the partition coefficient and selectivity of extraction.

Some organic matter or between organic matter and inorganic matter are dissolved in water at appropriate concentrations to form a two-phase or multi-phase aqueous system that is incompatible with each other as a two-phase aqueous system. This is an extraction method that separates targets and impurities according to their different partitioning ratios in the two phases.