Commercially available freeze-drying equipment

A wide range of apparatus exists that meets most laboratory needs as regards freezedrying. Below are described some of the more widely used designs. 

These are best exemplified by the Cryodos-50 and Cryodos-80 models from Telstar (Fig. 2.4), which consist essentially of the following elements  

This type of design is aptly exemplified by the Telstar models Lioalfa 6-50 and 6-80 (Fig. 2.6). Both are compact, benchtop apparatuses that accommodate the vacuum pump and cooling system. Also, both use the same type of vacuum pump as the Cryodos models. 

The cooling system consists of one or two air-tight, one-step compressors and uses air as coolant. 

Like the previous ones, the Lioalfa models can be equipped with aneillary devices for processing bulk products and samples in flasks, vials or ampoules. 

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Until atmospheric spray-freeze-drying equipment becomes commercially available, the development of formulation will be mainly based on the Trial and Error approach, and the validation of the classical lyophilization procedure will remain difLcult. 

A variety of small devices has been designed to meet specific functions not effectively served by commercially available freeze-dryers. Such devices were preceded by a number of customized dryers that were developed for various analytical purposes. Thus, Nakaguchi et al. [10] designed a new drying apparatus equipped with a device for trapping evaporated substances that was used to condition biological samples prior to determining trace elements. 

Walter and Bryant [414] described a method for freeze drying latex specimens in a home made vacuum system rather than a commercially available device (as was typical of the state of the art at that time). Later, a freeze drying/image analysis method using commercially available equipment was described [413]. Important details of that method included specimen preparation, placement onto a TEM (or SEM) grid, the hardware for the experiment and the metal coating. 

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