The sample of the lyophilizer eutectic point detection.
The so-called eutectic point, refers to the material in solution completely the temperature at which the freeze into ice crystals.
for freeze-drying technology, the determination of eutectic point is very important, is a main basis to make the freeze-drying curve.
Precool the product must be frozen at the temperature below the eutectic point, and sublimes products cannot exceed the eutectic point temperature, so the temperature of the eutectic point and sublimation products precool stage stage of highest temperature.
eutectic point measuring the resistance method is commonly used in the solution of the freezing process, by measuring the resistivity changes with temperature in the solution, to determine the eutectic point.
Solution of conductive belongs to the ionic conduction, as the solution to freeze, ion gradually are fixed, the resistance of the solution will gradually increase, when all freeze into solid, there will be a phenomenon of the sudden increase of resistance, the temperature of the solution at this time, is the eutectic point.
large lyophilizer (
Guangzhou customer probiotic freeze-dried use)
the resistance measurement method is only a means of rough, have special eutectic point tester is used for products of the eutectic point, at the same time frozen vacuum drying microscope, DSC and DTA method can accurately measure the eutectic point.
Considering the maneuverability of the preparation of the instruments and equipment and testing means, precool temperature is usually located in eutectic point below 5 ℃, under normal circumstances, the resistance measurement method can be used.
the discretion of the eutectic point is associated with the composition and concentration of solution, change the solution components and can change the eutectic point of solution concentration.
Because of the eutectic point high product easy to freeze, so you can by changing the components of the product and concentration to increase the temperature of the eutectic point of product.
the key requirement is in the process of freeze-drying control sample temperature keep 10 - below the eutectic point temperature
15 ℃, thereby ensuring the sample is not melting, maintaining the micro pore structure and physical and chemical properties remain intact.
Will now some common and eutectic point temperature data of samples freeze-dried sorting out, for your reference.
material
the eutectic point temperature ℃
material
the eutectic point temperature ℃
algae
-
15 - -
25
books archaeological relics
0 ~ 3
bacteria, viruses, fungi, vaccines,
-
40 or lower
plants, fish
-
15
the collagen
-
35
tissue sample
-
56
food: fruit, vegetables, meat
-
25
royal jelly and honey
-
40
ceramic powder
-
10
sludge
-
25
protein, enzyme, blood products,
-
13 ~ -
40
powder
-
13 (
Milk)
nucleic acids and polypeptides
-
30
organic solvents
below -
50
vegetable materials
-
10 (
Some -
30)
polymer materials such as material for medical use
-
2 ~ -
30
urine, feces, etc to do residue analysis
-
30
is given priority to with water containing a small amount of organic solvent or salts
-
2 ~ -
30
