The microporous filter membrane is a kind of macromolecule membrane material, which has many uniform micropores, and its pore size varies from 0.025 to 14 micron. Its filtration mechanism is mainly physical screening. There are many kinds of microporous membranes, such as cellulose acetate, polypropylene, and polytetrafluoroethylene.
The advantages of microporous filter membranes are high porosity, fast filtration speed, small adsorption, no retention of drug solution, no influence on drug content, simple equipment, easy removal, etc. The disadvantages are poor acid and alkali resistance, poor adaptability to some organic solvents such as propylene glycol, and the retained particles easily block the filter membranes and affect the filtration rate. The membrane can be used only after other filters have been preliminarily filtered.
Microporous filtration membranes are divided into organic membranes and water membranes. Organic membranes can pass through aqueous solutions, while water membranes can not pass through organic solutions.
There are different aperture specifications. One has a smooth surface, and some have no positive and negative sides. In general, 2,3 ml of primary filtrate is discarded before filtration, so as not to interfere with the detection of filter membrane impurities. After the steps of filtration, the adsorption of drugs on the lower filter membrane was investigated.
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