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Lyophilizer freeze dryer7/1/2023 To prevent vapors from entering the pump, make sure the collector coils have cooled to at least -40° C before the vacuum pump is started. Ensuring the compatibility of the samples to the freeze dryer, as discussed earlier, is the most important preventative step to vapors entering the pump. Combination rotary vane/diaphragm and scroll pumps are more resistant to harmful vapors but still can be damaged from exposure.ĭamage to any pump will be avoided by preventing vapors from entering the pump. Once mixed in the oil, water can cause extensive damage to a pump while solvents and acids can cause even more damage. Often the vapors will condense in the pump and mix with the oil. Oil vacuum pumps are the most susceptible to damage from these vapors. If the vapors are not completely collected on the coils in the collector, they will enter the vacuum pump. A damaged vacuum pump is the leading cause of inadequate vacuum levels in a freeze dry system. Maintaining deep vacuum levels is the most common problem in laboratory freeze drying. Particulates: Inline HEPA filters, placed between the collector and the vacuum pump, protect vacuum pumps from damage from particulates.Solvents: Glass lids are used when a solvent damages acrylic lids.Acids: Polytetrafluroethylene (PTFE) coatings protect stainless steel collectors and coils.Acids, solvents and particulates are common compounds that can be accommodated with modifications. Some samples may contain compounds that require special components in the freeze dry system. No harm is caused by using a collector that is bigger than the minimum size requirement. It is easier to make sure your entire run can be accommodated before starting the run. Stopping a run and defrosting the collector is not an ideal option. It is important to ensure the size of the collector is big enough to accommodate the volume of the entire sample load. No harm is caused by using a freeze dryer with a collector that is colder than the minimum requirement. For samples containing acetonitrile, a -84° C collector is recommended and for samples with up to 10% methanol, a -105° C collector is recommended. When solvents are present in samples, the freezing point is suppressed. For aqueous samples, a -50° C collector temperature is adequate. Collectors have fixed temperatures at -50° C, -84° C and -105° C. This difference is necessary to keep the sample frozen during primary drying and to effectively trap the lyophilized vapors before they reach the vacuum pump. The collector temperature of the freeze dryer is recommended to be 15° C to 20° C below the freezing point of a sample. Incompatibility can result in decreased quality of the freeze dried sample and, more importantly, expensive damage to the freeze dryer or vacuum pump.Īlthough it is not critical to know the precise freezing point of a sample, estimating the general freezing point or eutectic temperature of your sample is important. When lyophilizing, it is important to identify the components of the sample and their requirements for lyophilization. Often a sample is placed on a freeze dryer without any consideration as to the compatibility of the sample with the specifications of the freeze dryer. Following these suggestions can increase the quality of your samples and prolong the life of your freeze dryer. Once oil is chemically damaged, lubrication properties diminish and the vacuum pump quickly requires repair.Here are solutions for several common mistakes made in laboratory lyophilization. Vacuum pump oil can be quickly compromised by the vapors from a freeze dryer. Freeze-dryer applications require an ultimate vacuum of below 0.1 mbar, which can be achieved with two-stage rotary vane pumps or ChemStar Dry. Chemical resistance requirements for your freeze dryer vacuum pump depend upon the aggressiveness of your solvent. It is also important to clean the condenser after each run to prevent sublimation of frozen chemicals into the vacuum pump. If the pump’s flow rate is too high, then vapor will be pulled through the freeze-dryer’s condenser too quickly, reducing its efficiency. Vacuum pumps are required for this process, and should be sized according to the freeze-dryer. The method is often used to preserve food and pharmaceuticals, as it allows products to be easily stored and transported without requiring constant refrigeration. Freeze-drying, or lyophilization, is the process of freezing a material then sublimating any frozen liquid directly from solid to gas.
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