Operation Precautions of Microporous Membrane Filter

Microporous membrane filter operations include dead-end filtration (vertical flow filtration) and cross-flow filtration (tangential flow filtration). But no matter what kind of operation, there are precautions:

① Used for the determination of the bubble point
The determination of the bubble point pressure can reflect the pore size of the microporous filter membrane, which is closely related to the quality of the filtered liquid and is also an important means to ensure the quality of the microporous filter membrane.

Microporous membrane filter used should be soaked in water for injection at about 70℃ for 1 h in advance. Pour out the water and soak in warm water for injection overnight. Take it out before use, rinse it with water for injection, then put it into the filter for use. Prevent the filter membrane from leaking when installed.

② Service life extension
In order to protect and extend the service life of filter membrane, filter paper or silk cloth of the same size can be used (the silk cloth should be boiled with a mass concentration of 20 g·L-1 sodium sulfonate solution for about 30 minutes, and then washed with water for injection). Put it on the filter membrane to prevent it from breaking.

③ Pore size
The pore size is cone-shaped. There is a small pore size at the smooth and front side; the rough side has a larger pore size than the back side.

When installing, the front side (smooth side) should face up and the back side (dark side) down, otherwise it is easy to be blocked by impurities and affect the filtration rate.

When the temperature is low, the treated filter membrane should be soaked in water for injection at the same temperature as the drug solution for 5 to 10 minutes to avoid rupture caused by the drop in tensile strength of the filter membrane due to temperature differences.

④ Fix an infusion needle on the skin tube head of the exhaust pipe of the filter holder and control it with a water stop clip to prevent the exhaust pressure and speed from rupturing the filter membrane.

⑤ Do not sterilize the filter holder together with the filter membrane, otherwise the filter membrane may become brittle and crease due to thermal expansion and contraction.

⑥ After use, put the microporous filter membrane in water for injection to prevent it from drying, but do not soak for too long. It cannot be used after being dehydrated and dried.

⑦ According to the concentration and viscosity of the liquid medicine, microporous membrane filters with different pore sizes should be selected.

⑧ If you find that the microporous filter membrane has small holes or small cracks, you can rinse it with the unused broken filter membrane and dry it, then tear it up and place it in a small cup of acetone, stir it into a paste-like mucus. Drop it on the small holes or cracks of the flat filter membrane. It should not be too much. The mucus should be covered by a little larger one. After it dries, you can continue to use it without affecting it.

⑨ When using a multi-stage filtration device with coarse filtration and then fine filtration during infusion filtration, microporous membrane filters can be used for the final fine filtration, and pressure, decompression, and azimuthal static pressure filtration methods should be used.