Auxiliary extraction agent

1 The purpose of adding acid to the acid extraction solvent is to promote the extraction of alkaloids, improve the stability of some alkaloids, free the organic acid, facilitate the extraction with organic solvent, remove the acid insoluble impurities, etc In order to give full play to the best efficiency of the added acid, the acid can be added to the initial small amount of extraction solvent at a time When the acidification solvent is used up, the extraction operation can be completed smoothly only by using a simple solvent Commonly used sulfuric acid, hydrochloric acid, acetic acid, tartaric acid, citric acid, etc The amount of acid should not be too much to maintain a certain pH value 2 The application of alkali is not as common as that of acid The purpose of alkali addition is to increase the solubility and stability of the active ingredients For example, when liquorice is extracted, a little ammonia water is added to the water, which can make glycyrrhizic acid form soluble ammonium salt and ensure the complete extraction of glycyrrhizic acid In addition, if a small amount of ammonia water is added to the water during the extraction of Polygala tenuifolia, it can prevent the hydrolysis of acid saponins of Polygala tenuifolia and produce precipitation In addition, lactone, anthraquinone and its glycosides, coumarin, organic acids and some phenolic components can be dissolved in alkaline aqueous solution However, basic aqueous solution can also dissolve resin acid, some proteins, and increase impurities Alkali addition is the same as acid addition Ammonium hydroxide (ammonia water) is commonly used, because it is a volatile weak base, which has little damage to the effective components and is easy to control its dosage For special extraction, calcium carbonate, calcium hydroxide and sodium carbonate are often used 3 Glycerin is miscible with water and alcohol, but not with fat oil This product is a good solvent for tannin, which can be directly added to the initial small amount of solvent (water or ethanol) to increase the leaching of tannin; adding glycerin to the preparation mainly composed of tannin can enhance the stability of tannin 4 Adding appropriate surfactants in the extraction solvent can reduce the interfacial tension between the medicine and the solvent, reduce the wetting angle, promote the wettability of the medicine surface, and facilitate the extraction of some medicine ingredients If baicalin is extracted by boiling and alcohol precipitation, the yield can be increased by adding Tween-80.