Freeze drying lyophilisation

Microbial strains must be maintained in such a way that they do not lose their desirable characteristics. Some strains are maintained by regular subculturing, whereas others are lyophilised (freeze-dried), or frozen under nitrogen, or held at -80°C in a freezer. To ensure that a standard inoculum can be obtained on demand, great care is taken to ensure that foe stored cultures are pure and foe viability is known. 

Most enzyme powders are prepared by lyophilisation (freeze drying). However, the lyophilization procedure might inactivate the enzyme to some extent. To avoid this and thereby increase the activity of lyophilized enzymes in dry organic solvents, the lyophilization can be carried out in the presence of lyoprotectants such as sorbitol (Dabulis and Klibanov, 1993). The inactivation is believed to be caused at least partly by a reversible conformational change in the enzyme. This process can be reversed and the enzyme reactivated by the addition of small amoimts of water (Dabulis and Klibanov, 1993). 

The range of rubber materials includes natural and synthetic-based materials. Special designs of rubber (e.g. castellated) are available for lyophilised/freeze dried products. Surfaces may be coated, e.g. with PTFE or Parylene, to reduce any extractability risks. 

Pool, stabilise and formulate -Dispense into vials for clinical use -Lyophilise (Freeze-dry)... 

Freeze drying freeze drying or lyophilisation is one of the most practiced means of... 

Dissolve the active ingredient in the well stirred solution of Kollidon 12 PF and after freeze-drying, fill 500-mg-portions of the dry lyophilisate into ampoules. 

The method used depends largely on whether precise localisation is required or whether a certain amount of diffusion of the soluble compounds can be tolerated or is required. In the latter case rapid air drying (at 37°C) of cells labelled with tritiated thymidine allows thymidine phosphates to diffuse a little way to form a halo around the nucleus (Adams, 1969a). For precise localisation it is necessary to freeze the cells in isopentane or freon held at liquid nitrogen temperature and then to subject them to lyophilisation. This drying... 

H. Rupprecht, Physical-chemical basics of freeze-drying, in Lyophilisation. (Essig, Oschmann, ed). Scientific Publication Company, Stuttgart, 1993, p. 29. 

Solvent method - Spray-drying - Normal drying, Vacuum-drying - Freeze-drying, Lyophilization - Spray-drying of suspension Spray-embedded preparation Coprecipitate, coevaporate Lyophilisate Spray-dried suspension [538]... 

After freeze-drying, fill 550-mg portions of the lyophilisate into ampoules. 

During lyophilisation of any protein formulation, there is a need to include a lyoprotectant such as polyols to prevent freeze-drying-induced denaturation. 

Lyophilised ATP standards are commercially available. However, part of the freeze-dried material is often lost with the freeze-drying stopper. We have overcome this by providing ready-made, stabilized liquid ATP standards (Fig. 1). 

This treatment is especially recommended if the cells are lyophilised for deuterations. The cells can be lyophilised without loss of hydrogenase and enoate reductase activity. Without this treatment usually 60-80 % of the enzyme activity can get lost during freeze drying, even if contact with oxygen is tried to omit. Freeze dried cells are used for reductions in H20. 

LOEL lowest-observed-effect level LOQ limit of quantification lyophilisate product of freeze drying lysosome cell organelle containing hydrolases (hydrolytic enzymes) it is active in phagocytosis, i.e. in intracellular digestion and destruction accompanied by release of the cell contents... 

Methods commonly used for determining the elemental content of these biota samples include AAS, NAA, DPASV and ICP-AES. A pretreatment step is almost always necessary. The samples of urine should be acidified with a mineral acid or acetic acid for temporary preservation. The samples should, however, be freeze-dried or lyophilised for long term storage. It is possible to determine a number of elements in urine by diluting the samples with deionised water and aspiration into a flame or plasma. 

The freeze dried or lyophilised samples of excreta can be digested at low temperatures (170-210°C) for 15-20 min with a minimal acid mixture of nitric and perchloric (1 2). Though this procedure can not destroy the organic matter completely, it should be at least as effective as the mineral acid extraction procedures described for excreta samples (Riner et al.. 1974). Maurer (1977) also found better results by extracting the specimens with a mixture of nitric (65%). hydrochloric acid (25%) and water (3 27 20) compared to those obtained by dry ashing. 

The urine samples are usually treated with a mineral acid e.g. HCI, HNO3 or acetic acid for temporary preservation. However, for long term storage these human specimens need to be frozen, lyophilised or freeze-dried. Fecal samples should almost always be lyophil-ised or freeze dried before treatment. 

Using ICP-MS we found that the iodine concentration of pork, beef and mutton was in the range < 1.6-16 pg/kg (Schone et ai, 2002). The lower limit (<1.6pg/kg) represents the threshold for quantification of iodine as a result of freeze-drying weighed fresh meat, analysis of the ground lyophilisate, and recalculation of the results for the fresh meat. A threshold for quantification of 6.63 Pg/kg lyophilisate corresponds to 1.6pg-iodine/kg fresh meat (Schone et ai, 2006c). 

Chatigny and Clinker compared common laboratory accidents and showed that exposure to a broken vial of lyophilised bacteria was particularly hazardous. While the precise magnitude of their assessment may be a matter for discussion there is no doubt that handling freeze-dried cultures of pathogens or toxins may constitute a significant hazard. ... 

J Hallet. Nucleation and growth of ice crystals. In L Rey, ed. Advances in Freeze-drying Lyophilisation. Paris Hermann, 1966, p 33. 

L Rey. Orientations nouvelles de la lyophilisation. In L Rey, ed. Research and Development in Freeze-Drying. Paris Hermann, 1964, pp 63(E643. 

Tablets are defined in the Ph. Eur. as solid preparations each containing a single dose of one or more active substances [6]. Tablets are prepared by compressing tmiform volumes of particles or by another suitable manufacturing technique, such as extmsion, moulding or freeze-drying (lyophilisation). The Ph. Eur. distinguishes various types of tablets the most important being uncoated tablets, coated tablets, effervescent tablets, dispersible tablets, gastro-resistant tablets and modified-release tablets.

Slater, N. K. H., 2003. Measurement of lyophilisation primart drying rates by freeze-drying microscopy. Chem. Eng. Sd. 58 2313-2323. 

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