Used vacuum freeze dryer
Used vacuum freeze dryer
The vacuum freeze dryer is suitable for drying high-grade raw materials, Chinese herbal medicines, biological, wild vegetables, dehydrated vegetables, food, fruits, chemicals, pharmaceutical intermediates and other materials. Freezing vacuum drying is a new type of box structure that combines the refrigeration system, vacuum system, heat transfer oil heating system and dehumidification system into a vacuum freeze dryer. It uses the freezer vacuum drying to store the material space in the box.
Introduction
1. Vacuum freeze dryer is suitable for drying high-grade raw materials, Chinese herbal medicines, seafood, wild vegetables, dehydrated vegetables, food, fruits, chemical intermediates and other materials. [1]
2. The vacuum freeze dryer combines the refrigeration system, the vacuum system, the heat transfer oil heating system, and the moisture discharge system. A new type of box structure is used to dry the vacuum vacuum drying of the material space in the tank. The powder has good dispersibility.
Characteristics
In the freeze vacuum drying process, no impurities are mixed into the object, and the original components and active ingredients of the material and the shape of the material are not damaged.
working principle
After the start-up, the material is put into the material box for freezing. The freezing process of the material, on the one hand, the vacuum system is vacuumed to take away part of the water; on the other hand, when the material is frozen, the moisture in some molecules is discharged. The surface of the material is frozen. After the freezing requirement is reached, the material is heated and dried by the heating system, and the water contained in the material is brought to the freezing trap box by vacuuming to achieve the freeze-drying requirement of the material.
Freeze drying refers to the process of removing moisture or other solvents from frozen biological products by sublimation. Sublimation refers to the process of solvents, such as water, like dry ice, which does not pass through a liquid state and changes from a solid to a gaseous state. The product obtained by freeze drying is referred to as a lyophilizer, and the process is referred to as lyophilization. Traditional drying can cause the material to shrink and damage the cells. The structure of the sample is not destroyed during the freeze drying process because the solid component is supported by the firm ice at its location. When the ice sublimes, it leaves pores in the dry remaining material. This preserves the biological and chemical structure of the product and the integrity of its activity. In the laboratory, lyophilization has many different uses and is indispensable in many biochemical and pharmaceutical applications. It is used to obtain biological materials that can be preserved for a long period of time, such as microbial culture, enzymes, blood, and pharmaceuticals, in addition to the long-term preservation stability, retaining its inherent biological activity and structure. To this end, lyophilization is used to prepare tissue samples for structural studies (eg, electron microscopy studies). Freeze drying is also used in chemical analysis to obtain dried samples or to concentrate samples to increase analytical sensitivity. Freeze-drying stabilizes the sample composition without changing the chemical composition, which is an ideal analytical aid. Freeze drying can occur naturally. In the natural case, this process is slow and unpredictable. Through the freeze-drying system, people have improved and subdivided many steps to speed up the process.
classification
Structurally
Bell-type freeze-drying machine: The freeze-drying chamber and the cold trap are separate upper and lower structures, and the freeze-drying chamber has no pre-freezing function. This type of lyophilizer requires manual operation when it is transferred to the drying process after the material has been pre-frozen. Most of the experimental freeze dryers are bell-type, which has a simple structure and low cost. Most of the freeze-drying chambers use a transparent plexiglass cover to facilitate the observation of the lyophilization of the material. [2]
In-situ freeze-drying machine: the freeze-drying chamber and the cold trap are two independent cavities. The shelf in the freeze-drying chamber has a cooling function. After the material is placed in the freeze-drying chamber, the pre-freezing and drying process of the material does not require manual operation. . This type of freeze dryer has a complicated manufacturing process and high manufacturing cost, but the in-situ freeze dryer is the development direction of the freeze dryer, and is an ideal choice for lyophilization process, especially suitable for medicine, biological products and other special products. Freeze-dried.
a, ordinary b, multi-manifold c, gland type
Functionally
Ordinary shelf type: The material is bulk in the material tray and is suitable for lyophilization of food, Chinese herbal medicine and powder materials.
With gland type: suitable for the drying of the bottled material of Xilin. When lyophilizing, prepare the material in the vial as needed, float the cap and freeze-dry it. After drying, operate the gland mechanism to compress the cap. It can avoid secondary pollution, re-adsorb moisture, and is easy to store for a long time.
Multi-manifold type: The flask is attached to the outside of the drying chamber, and the material frozen on the inner wall of the bottle is dried. At this time, the flask is connected as a container to the manifold outside the drying box, and the material in the flask is heated at room temperature, and the mixture is heated. The tube switch device can be removed or loaded at any time as needed without stopping the machine.
With pre-freezing function type: material pre-freezing process, cold trap as pre-freezing chamber pre-freezing material, in the drying process, the cold trap is a water trap, capturing the moisture overflowing the material. The lyophilizer with pre-freezing function, the pre-freezing and drying of the materials in the freeze-drying process are all completed on the lyophilizer, and the lyophilizer has high use efficiency, which saves the cost of the low-temperature refrigerator.
Several parameters that should be paid attention to when purchasing a freeze dryer
Freeze-dried area
The number in the lyophilizer model represents the lyophilization area of ​​the lyophilizer of this model. For example, the lyophilized area of ​​the LGJ-18C lyophilizer is 0.18 m2. The user should calculate the lyophilizer for the lyophilized area according to his own needs. For example, for each batch of products that require lyophilization of 1.8 kg (liter) of liquid, and loading the material with a material tray, each loaded with 10 mm thick, the load area of ​​the lyophilized layer can be calculated:
A (area, m2) = V (volume, m) / H (height, m) = 0.0018 m / 0.01 m = 0.18 m2
A lyophilizer with a lamellar load area of ​​0.18 m2 is required.
Cold trap temperature
The cold trap is a device for capturing moisture in the freeze-drying process. Theoretically, the lower the temperature of the cold trap, the stronger the water trapping ability of the cold trap, but the lower the temperature of the cold trap, the higher the requirements for refrigeration, the higher the machine cost and the running cost. The cold trap temperature of the experimental series freeze dryer mainly has several grades of about -45 °C, -60 °C, and -80 °C. Freeze-drying at -45 °C for some freeze-dried products, freeze-drying machine with a cold trap temperature of -60 °C for lyophilization of most products, freeze-drying at -80 °C Suitable for lyophilization of some special products. The effect of cold trap temperature on water-trapping capacity shows that the temperature of the cold trap drops from -35 °C to -55 °C, and the water-trapping capacity is obviously improved. The cold trap temperature is lower than -55 °C, and the water trapping capacity of the cold trap is not significantly improved. Therefore, in the absence of special needs, the choice of cold trap temperature -60 ° C is the ideal choice. The cold trap temperature of the LGJ-10D freeze dryer in the four-ring freeze dryer is ≤-55 °C, and the freeze dryer temperature of the LGJ-18 series and LGJ-25 series is ≤-60 °C, and the refrigerant is mixed with mixed refrigerant. The technology, in the case of the same refrigeration unit, has a low cooling temperature, a large cooling capacity, a high operational stability, and a low failure rate. The four-ring lyophilizer also includes the LGJ-10 freeze dryer with cold trap temperature ≤ -45 ° C, suitable for lyophilization of some freeze-dried products. The cold trap temperature of LGJ-50C freeze dryer is ≤-80 °C, which is especially suitable for lyophilization of medicines and special products. [3]
3, cooling rate
The cooling rate reflects the cooling capacity of the refrigeration system. Under no-load conditions, the cold trap temperature should reach the low temperature specified by the index within 1 hour. For example, a lyophilizer with a cold trap temperature ≤ -60 ° C, the machine starts from the time of opening the refrigeration, and the cold trap temperature reaches -60 ° C for no more than 1 hour.
4, the ultimate vacuum
The ultimate vacuum reflects the leakage of the freeze dryer and the pumping efficiency of the vacuum pump. The degree of vacuum of the freeze-drying box, the past view that the higher the degree of vacuum, the better, the industry's view that the degree of vacuum should be within a reasonable range. The degree of vacuum is too high, which is not conducive to heat transfer, but the drying speed is reduced, but the vacuum limit of the freeze-drying box should reach 15Pa or more.
5, vacuum time
The emptying speed of the freeze-drying box should be pumped from atmospheric pressure to 15Pa within half an hour.
6, the layer temperature uniformity and flatness:
The uniformity and flatness of the lamellar temperature have a great influence on the uniformity of product quality. The better the temperature uniformity and the flatness, the better the uniformity of the quality of the freeze-dried product. The lyophilizer shelf temperature control has a heater type and an intermediate fluid type, and the freeze-drying machine shelf with the intermediate fluid control plate layer has uniform temperature uniformity and flatness, and the lyophilizer layer is a hollow sandwich structure, the slab layer The cooling and heating are achieved by circulating the intermediate fluid in the fluid channel inside the ply, so the temperature of the ply is uniform. The LGJ-50C freeze dryer in the four-ring freeze dryer uses the technology of the intermediate fluid in the shelf. The shelf temperature control of the bell-type lyophilizer is basically a heater, and the temperature uniformity of the plate layer is slightly poor. However, in general, the temperature difference of the lyophilizer for medical use should be controlled at ±1.5 °C, the temperature difference within the plate is ±1 °C, and the food freeze dryer can be appropriately relaxed.
7, control system
The type and function of the control system of the freeze dryer are different. For the freeze dryer of the experimental series, it is mainly applied to the lyophilization process of the material and a small amount of trial production. Therefore, the control system should display the parameters of the freeze-drying process in real time and record automatically; set, modify and effectively execute the freeze-drying process program; have a communication interface to facilitate data collection and storage.
PCR ( Polymerase Chain Reaction)
It provides a way to make more copies of a portion of DNA.
We need to have PCR ingredients that include DNA portion, Buffer solution, Primer+DNA (tap polymerase), and Nucleotides during the preparation step.
In the step of PCR sequence, there are three steps in this section.
Step 1 Denaturation
The addition of heat is needed to separate the two strands of the DNA molecule.
Step 2 Annealing
Temperature, is going to be cool in this step, should allow the primers to bind to the specific segments.
Step 3 DNA Synthesis
To make more copies of the DNA.
Those three steps above keep repeating to make enough copies of the DNA fragments. It is the principle of how PCR machine works.
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