Labconco FreeZone Clear Stoppering Chambers - Manual (Page 8)

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Chapter 1: Introduction
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If there is a problem with a particular type of sample melting when
placed on the freeze dry system, dilution of the sample with more
water or providing some insulation around the flask to decrease the
rate of heat absorption by the sample may help. If the eutectic
temperature of the sample is –40 to –60°C, the freeze dry system
selected for use must be equipped with cascade type refrigeration
so that the collector temperature can be cooled to below –75°C, or
a dry ice/solvent trap may be used between the collector and the
vacuum pump.
Samples Containing Volatile
Substances
In certain cases the solvent in a sample to be freeze dried may
contain volatile components such as acetonitrile, methanol, acetic
acid, formic acid or pyridine. In addition to these substances
having an effect on the eutectic temperature, they may increase the
vapor pressure at the surface of the sample. Also, compared to
water, they will require the absorption of less heat for sublimation
to occur. Hence, samples that contain volatile substances will have
a greater tendency to melt, particularly when placed in flasks or
exposed to room temperature. If a sample containing a volatile
substance tends to melt when placed on a freeze dry system,
dilution of the sample with more water will help keep the sample
frozen. For example, a 0.2M solution of acetic acid is much easier
to freeze dry than a 0.5M solution.
About This Manual
This manual is designed to help you learn how to install, use, and
maintain your Clear Stoppering Chamber.
Chapter 1: Introduction provides a brief overview of the freeze dry
process, explains the organization of the manual, and defines the
typographical conventions used in the manual.
Chapter 2: Prerequisites explains what you need to do to prepare
your site before you install your Clear Stoppering Chamber.
Electrical requirements are discussed.
Chapter 3: Getting Started contains the information you need to
properly unpack, inspect and install your Clear Stoppering
Chamber.