What are the laboratory freeze-drying experimental steps for freeze-drying samples?
The laboratory freeze-dryer sample freeze-drying experimental steps are mainly divided into two steps: sample pre-freezing and sample drying! Laboratory freeze dryer devices are available in ordinary type, gland type, multi-manifold type, and in-situ type. Different devices have different lyophilization operations.
Below, Beijing Songyuan, a Chinese freeze-drying equipment supplier, takes an ordinary freeze-dryer as an example to describe the sample freeze-dryer experimental steps:
I. Pre-freezing process operation
Note: This step can be omitted for users with low temperature refrigerators
(1) Turn on the refrigerator and pre-cool the equipment. When the temperature of the cold trap drops below -40 ° C, the materials can be pre-frozen;
2 (2) Put the material into the material tray (liquid is directly injected into the material tray, and solid or bottled materials can be evenly placed on the material tray);
3 (3) Put the material pan into the pre-freezing rack, and put the probe into the material pan to make full contact with the material to reduce the error between the sample temperature and the actual temperature;
(4) Put the pre-freezing rack into the cold trap;
(5) Put on the heat preservation cover;
(6) After pre-freezing until the temperature of each part of the material drops below the eutectic point of the material, pre-freezing can be completed for about 1 hour, and it is ready to enter the drying stage.
Second, the operation of the drying process
(1) Remove the pre-freezing rack from the cold trap;
(2) Take out the pre-frozen material and put it on the drying rack;
(3) Place the drying rack on the cold trap, as shown in the figure;
(4) On the premise that the seal ring is intact and free of debris, cover the "plexiglass tube";
(5) Tighten the drain valve clockwise;
(6) Turn on the vacuum pump and the vacuum gauge. The degree of vacuum decreases. Generally, the value of vacuum degree <20pa during the drying process is normal.
(7) After the drying is completed, first open the "water discharge (intake) valve" and then close the "vacuum pump". Remove the plexiglass cylinder and collect the dried matter.
(8) Close the "water (intake) valve" to defrost the equipment. After the defrost is completed, open the "water (intake) valve" to drain and wipe the device clean.
(9) When the vacuum pump is not working, please cover the exhaust hole to prevent dust from entering.
Note: a. The refrigerator must not be turned off during the entire drying process;
B.Due to differences in material characteristics, there are differences in drying and pre-freezing time.
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