A Simple System for Freeze Drying
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Herein is described a s i m d e svstem to freeze drv small ouantities of material. The aooaratus is similar to the se, . ries of vacuum traps mutinel) used for vacuum di.+ttllati~n. hlust bf the equipm~ntshould he readily available in the Iabumtorv. The system illuitrntrd in the fiyurc is ronitructrd .o rhsr a~mulraneousfreeze drymp of tuo samples is pos3rhle However, the deqign is readily adaptable to nvahhle equrpment. Standard sepamble vncuurn traps nrr used
Quickseal valves (VirTis, 'h in. O.D.) are attached to traps A and B a t the indicated positions. Vacuum tubing is attached as shown so that the inner tubes of traps A and B are connected via a T-joint to the inner tube of trap C. A three way stopcock is placed a t a convenient point between the T-joint and trap C. The outer tube of trap C is then connected to the vacuum pump. Standard screw clamps are used to secure a tight fit between glass and vacuum tubing. It should be noted that the vacuum hose leading from traps A and B to the pump is connected in a manner revene of that used in vacuum distillation. This allows greater surface area for condensation. Trap C is connected in the "normal" manner since its only function is to mevent traces of water from being pulled into the pump. In the normal operation of the apparatus the sample is placed in a Quickseal flask (VirTis; 19/38) and frozen in the acetone-dry ice bath. Traps A'and B are clamped in place so that they extend as far as possible into the bath. The flask is then attached to the Quickseal valve and the system is evacuated. The construction of the valve allows independent removal of samples without affecting the vacuum system. The system can be tested for leakage by momentarily attaching a manometer to the sir inlet ofthe three way stopcock. Published with the approval of the Director of the New Hampshire Agricultural Experiment Station as scientific contribution r688. Financial support was provided by the U.S. Department of Interior as authorized under the Water RRources Research Act of 1964, Public Law 88-379. Brian M. Kilcullen Robert D. Harter Institute of Natural a n d Environmental Resources University of New Hampshire Durham, New Hampshire 03824
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Journaiof Chemical Education
