Freeze-dryer balances

Annealing below T did not result in increased drying rates. Based upon that finding the authors proposed a new aimealing-lyophilization method of T determination which can be carried out with only a balance and a freeze-dryer, measures T over any time scale desired, and has the additional advantage that a large number of candidate formulations can be evaluated simultaneously [4]. 

Reference 10 lists frequencies and parameters to be checked for chromatographs including liquid and gas chromatographs, electrodes, and for heat-ing/cooling appai atus including freeze dryers, freezers, furnaces, hot air sterilizers, incubators, for spectrometers, autosamplers, balances, volumetric glassware, hydrometers, barometers, and thermometers. 

While the sensors described in the previous paragraph allow monitoring of only single vials, a balance placed directly in the vacuum chamber of the freeze-dryer allows monitoring of a group of vials the direct weight measurement enables the... 

Fig. 4.5 Sketch of the balance for freeze-dryers (Vallan et al., 2005b Vallan, 2007).

Fig. 4.6 Example of results obtained during a freeze-drying cycle using the special balance with the embedded wireless temperature measurement in order to monitor the primary drying stage of a mannitol-dextran solution (6-14% by weight) in a pilot-scale freeze-dryer. The freezing stage was run at 223 K for about 5 h, while the main drying was carried out setting the fluid temperature at 293 l< and the chamber pressure at 10 Pa (Nv = 98 on tray, dv= 14.2 X 10 m, Lp = 7.2 x 10 m).

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