Labconco FreeZone 2.5 Liter Freeze Dry Systems 76705 Series - Manual (Page 25)

Chapter 4: Using Your Freeze Dryer
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of the sample. Adjustments to the vacuum level must be made for various freeze
drying conditions. Factors that must be considered are whether the sample is
freeze dried on heated shelves or in glassware attached to manifold valves, the
volatility of the sample itself, the size of the sample and the heat energy supplied
to the sample.
Some guidelines for setting the freeze dryer are shown below. These show pre-
freezing temperatures and vacuum levels. Exact protocols must be determined by
the user for the specific samples that are being freeze dried.
When the vacuum control is set to operate at less vacuum, the ice holding capacity
of the collector may be decreased. This can be improved by installing a baffle in
the collector. See Appendix D Freeze Dry Accessories for the baffle part number.
See the section titled Baffle in this chapter for the proper installation.
Material
Solidification/Eutectic
Temperature
Pre-Freeze
Temperatures
Vacuum Set Point
Bacteria,Virus -40°C and Colder -50°C &
Colder
0.040 mBar &
Lower
Milk -5 to -13 -15 to -23 1.65 to 0.77
Fungi -40 and Colder -50 & Colder 0.04 and lower
Vegetable Tissue -25 to -50 -35 to -60 0.22 to 0.01
Human Tissue -30 to –40 -40 to –50 0.12 to 0.04
Blood Plasma -10 to –25 -20 to –35 1.03 to 0.22
Vaccine -30 to –40 -40 to –50 0.12 to 0.04
Pre-Freezing Samples
Appropriate containers for freeze drying include ampules, serum bottles, and wide
mouth freeze drying flasks. Shell freezing of samples is recommended for wide
mouth freeze drying flasks. Smaller samples in ampules and serum bottles may be
frozen in a freezer or in the center of the collector chamber. The sample container
size should always be at least two to three times the sample size (i.e., 40 ml
samples should be prepared in 80 ml containers or larger). The temperature
required for pre-freezing is dependent on the characteristics of the sample. Pre-
freezing temperature typically is at least 10° to 20°C below the eutectic or collapse
temperature of the sample.
Adding Sample
The following procedure should be followed when using sample valves in the
freeze dry process:
1.
Connect a pre-frozen sample to a sample valve on the drying chamber or manifold
using an adapter. Turn the plastic valve knob to the “VACUUM” position to open
the valve, which connects the attached sample to system vacuum. The bevel on the
knob should be positioned toward the sample port to apply vacuum to the sample.