Freeze-drying laboratory

Freeze-drying of aequorin. The process of freeze-drying always results in some loss in the luminescence activity of aequorin. Therefore, aequorin should not be dried if a fully active aequorin is required. The loss is usually 10% or more. The loss can be somewhat lessened by adjusting the buffer composition the use of 100 mM KCl and some sugar (50-100 mM) seems to be beneficial. The buffer composition used at the author s laboratory is as follows 100 mM KCl, 50 mM glucose, 3 mM HEPES, 3 mM Bis-Tris, and at least 0.05 mM EDTA, pH 7.0. 

Once a suitable strain is available, the prachce is to grow, often ftom a single organism, a sizeable culture which is distributed in small amounts in a large number of ampoules and then stored at 70°C or freeze-dried. This is the seed lot. From this seed lot, one or more ampoules are taken and used as the seed to originate a limited number of batches of vaccine which are first examined exhaustively in the laboratory and then, if found to be satisfactory, tested for safety and efficacy in clinical trials. Satisfactory results in the clinical trials validate the seed lot as the seed from which batches of vaccine for routine use can subsequently be produced. 

Lack of repeatability of the results of metabolic studies using laboratory strains that have been maintained by repeated transfer for long periods under nonselective conditions may be encountered. These strains may no longer retain their original metabolic capabilities, and this may be particularly prevalent when the strains carry catabolic plasmids that may have been lost under nonselective conditions. For these reasons, strains should be maintained in the presence of a cryoprotectant such as glycerol at low temperatures (-70°C or in liquid Nj) as soon as possible after isolation. Freeze-drying is also widely adopted, and is recommended. 

Frozen reference materials have been produced by NIST (Wise et al. 1993). These materials do not have the disadvantages of the oils or freeze-dried materials, but are more difficult to transport. Obviously they have to be kept deep-frozen during transport, which makes their use rather expensive. Since the early 1990 s a new approach in this field has been introduced. This concerned the use of wet, sterilized fish and shellfish samples. These samples, packed in glass jars or in tins, were firstly used in the QUASIMEME program as reference materials for inter-laboratory studies (de Boer 1997). Later, when it appeared that the stability was maintained for longer periods, tests for organic contaminants based on this principle were also prepared. 

MJ Pikal. Use of laboratory data in freeze drying process design Heat and mass transfer coefficients and the computer simulation of freeze drying. J Parenter Sci Tech-nol 39 115-138, 1985. 

In most laboratory-, pilot- and production plants, in which the content of vials and trays are freeze dried, the shelves can be cooled to - 10 °C or -50 °C, while in special plants -60 °C or a little less can be reached. The containers can be loaded onto precooled or room temperature shelves (Fig. 1.80.1-1.80.3). The possible freezing speeds can be estimated per... 

It is likely asked too much of most laboratory plants, if used as pilot plants for production process development. The best application of laboratory plants is the freeze drying of preparations and products which do not require to be operated within small tolerances, but can be dried under noncritical process data. 

A member of the Aryan Nations neo-Nazi organization was arrested in Ohio on charges of mail and wire fraud. He allegedly misrepresented himself when ordering three vials of freeze-dried Yersinia pestis, a bacterium that causes plague, from a Maryland biological laboratory. 

EAAm was synthesized in our laboratory as described previously [24]. Copolymers of DMAEMA and EAAm were prepared by free radical polymerization as follows 7.8 g of distilled monomers (mixtures of DMAEMA and EAAm) and 0.02 g of AIBN as an initiator were dissolved in 100 mL of a (50/50 by volume) water/ethanol mixture. The feed compositions for poly(DMAEMA-co-EAAm) are shown in Table 2. The ampoule containing the solution was sealed by conventional methods and inunersed in a water bath held at 75°C for 15 h. After polymerization, all polymers were dialyzed against distilled-deionized water at 4°C and freeze-dried. 

Freeze-Dried Samples. Solid Materials and Tissues. These are first cut into approximately 1-inch cubes, frozen on a Teflon cookie sheet in a freezer, and placed in 1200-ml. freeze-dry flasks to capacity. The flasks are attached to the freeze-dried (lyophilizer) manifold, the valves are opened to vacuum, and the flasks are evacuated. The water from the tissues is trapped on a condenser. The dry tissues (drying time about 2-3 days) are removed from the lyophilizer and compressed into thin-walled aluminum cans with a Carver Laboratory press fitted with a special die, at about 24,000 lb. pressure (total). From 150-250 grams of the dry material, representing 500-1000 grams of fresh tissue, can be packed into a single can. The cans are sealed with a hand sealer and set aside for counting. Samples can be removed from the cans at a later date for chemical analysis or beta-emitter analyses. 

As with any laboratory method, there are precautions and limitations of lyophilization that must be understood. Only aqueous solutions should be lyophilized. Organic solvents lower the melting point of aqueous solutions and increase the chances that the sample will melt and become denatured during freeze-drying. There is also the possibility that organic vapors will pass through the cold trap into the vacuum pump, where they may cause damage. 

Freeze-dried powdered plant material, ground with a blender (e.g., Waring) or laboratory mill (e.g., Thomas-Wiley) and stored at -18°C under nitrogen gas, protected from light 80% (v/v) aqueous methanol Nitrogen gas Absolute methanol... 

Fig. 2.57. Laboratory freeze-drying plant. Microprocessor controlled, air-cooled compressor, condenser end temperature-53 °C, 3 kg of ice sublimed in 24 h. (a) Unit with 8 valve connections for 8 containers, condenser in an...

Fig. 3.11. Scheme of a laboratory freeze-drying plant. 1, Vacuum chamber with tempered shelves 2, container with probe 3, lift for shelves 4, condenser 5, lockgate 6, balance in the lock 7, vacuum pump for the lock ... 

The book describes the up-to-date fundamentals of freezedrying, not just presenting the process in all its seven steps theoretically, but explaining it with many practical examples. Many years of experience in freeze-drying allow the authors to supply valuable criteria for the selection of laboratory, pilot and production plants, discussing the advantages, drawbacks and limitations of different plant designs. 

At the Survey base or laboratory, the samples should be completely dried at < 40°C. Freeze drying is a recommended as this helps to disaggregate the samples. Dried samples should be sent to LAB I. 

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