What is the "bottle spraying" phenomenon of laboratory freeze-drying machines?
The laboratory freeze-drying machine adopts an imported fully enclosed refrigeration unit, with low temperature and strong water capture capacity. The vacuum connection adopts international standard parts, with simple and convenient disassembly and installation and reliable sealing performance. The specially designed touch soft key can quickly and accurately realize the function setting, and the operation is simple and convenient. High-quality stainless steel sample rack, ordinary sample tray spacing is adjustable, and the number of layers can be set freely. Stainless steel cold trap and table, sanitary, easy to clean, beautiful, and corrosion-resistant.
The bottle spraying phenomenon of laboratory lyophilizer is an important factor affecting the appearance quality of lyophilized preparations. The reasons for bottle spraying mainly include three aspects: bubbles in liquid medicine, pre-freezing, and drying rate.
During the sub packaging of products, when the solution is injected into the bottle, a certain amount of bubbles are formed in the liquid in the bottle due to the rapid flow rate of the liquid. At this time, the bottled liquid should be placed for a certain time to fully escape the bubbles, otherwise, the bubbles will be frozen inside the products. When the sublimation process is vacuumized and depressurized, the gas will escape and some products will adhere to the bottle wall. In the freezing process, the pre-freezing temperature is not low enough or the holding time is not long enough, which fails to solidify all the solutions. When the solution is sublimated and dried in a vacuum when the temperature of the solution reaches the eutectic point, the solution and water crystallize and precipitate at the same time, and the liquid boils, resulting in a bottle spraying. The pre-freezing temperature shall be strictly controlled. The pre-freezing temperature shall be 15 ℃ lower than the eutectic point temperature, and the freezing compaction can be ensured by maintaining it for 2-3H.
The temperature rise is too fast, resulting in a too-large temperature difference between the top and bottom of the product. The crystallization of the lower product is not sublimation from solid to gas, but evaporation from solid, liquid to gas to form a spray bottle. In this way, the product is uneven, loose, and spongy, while the lower part is hard and has irregular holes, which can cause the product to be scrapped in serious cases. Therefore, the heating rate in the sublimation drying stage, especially near the eutectic point, should be strictly controlled, uniform, and not too fast.
