Freezing method

Commercial butane and commercial propane shall not contain free or suspended water on visual inspection. Additionally, for commercial propane, the content of dissolved water shall not be such as to cause failure when tested in accordance with the valve freeze method. 

Freezing method freezer down to precooled shelves, ... 

The freezing of liquids in vials, bottles or flasks in a liquid bath is the most common freezing method used in laboratories. As the liquid must have a low melting point, alcohol (ethanol, melting point -114 °C) cooled by C02 (boiling point -80 °C at 1 atm) is frequently used. The bath can also be cooled by refrigerated coils. 

Freezing method and freezing rate must be the same. 

Figure 3.1 shows the influence of different freezing methods on the activity of a recombinant DNA protein. However, in the case of other macromolecules, for example a monoclonal antibody, there may be exceptions from the rule and different factors (e. g. pH-value) play an important role. 

Plunge freezing Plunge specimen into a container of cryogen with forceps cell suspensions can be adhered to coverslips coated with poly-L-lysine design of cryogen baths is important (27) baths are cheaper than other freezing methods... 

Robards AW. Rapid-freezing methods and their application, in Electron Microscopy of Plant Cells (Hall JL, Hawes C, eds.), Academic Press, London, UK, 1991, pp. 257-312. 

Bray who has pioneered the rapid freeze method for studying fast kinetics, has recently used this method in conjunction with XAS The procedure involves quenching reacting solutions by squirting them into a cold imiscible solvent and allows the preparation of a series of samples, each frozen at a particular reaction time (from about 3 ms upwards). Bray and co-workers used this method to Study the structural... 

TABLE I COMPARATIVE PERFORMANCE OF FREEZING METHODS FOR SELECTED SUBSTANCES... 

Freezing method Freezer down Precooled shelves, -45 °C... 

Fig. 2.1. Freezing methods. 1, Shell-freezing a flask is placed in cold bath in such a way that the neck of the flask is covered by the liquid. A motor turns the flask and the product freezes on the wall. 2, Spin-freezing one or more bottles are fixed to a jig and immersed in the bath. The jig turns the bottle(s) so fast...

Fig. 2.90. Tice of a 10% saccharose solution as a function of MD time with different number of vials, freezing methods and different 7"sh, d = 10 mm, pc = 0.15 mbar...

The influence of the freezing method the loading of the vials on C or W shelves influences the freezing rate (not shown) marginally on precooled shelves (C) the rate was between 0.65 and 0.40 °C/min and on warm shelves (W) between 0.25 and 0.40 °C/min with LN2 30-65 °C/min have been reached. Tfc during MD is only... 

The relative small differences in 71 for this product by layer thickness, load, freezing methods and additional ions should not be overlooked because of their consequences. The drying time is close to proportional to d in the range between 8 and 20 mm and the influence of pc is decisive for the freeze-drying process, but also the other factors are important as can be seen more clearly from the DR measurements during SD. 

Fig. 2.92. Desorption rates (DR) as a function of total drying time. 100 vials filled with 10% albumin solution, with different freezing methods, different pc and product thickness.

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