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Page 15 of 25 SPEX SamplePrep LLC 9.24.07
Note that there are three different sizes of vial that can be run in the 6870 Freezer/Mill: Large,
Mid-Size, and Small. Mid-Size vials must be run with a 6886 Adapter in the coil, and Small
vials must be run with a 6806 Adapter in the coil. Large vials do not need an Adapter. See
Section 4.4 for details.
With the vial or vials (and adapter) in place, loosen the coil gate handle a turn or two
counterclockwise, align the handle with the slot, close the gate, and turn the handle clockwise
until the gate is in snug contact with the vial or vials. To lock the gate, fold down the gate
handle against the gate. Do not overtighten the gate, as this can crack the vial’s center
section.
If the Freezer/Mill tub is empty, pour liquid nitrogen (LN) into the tub about a third of the way.
Initially LN will boil off vigorously, but as the tub cools the boiling will subside. Add more LN
gradually, to avoid splashing and boiling over. When the LN is up to the fill mark and boiling is
subdued, push the lid down gently until the bottom of the latch can be engaged; the lid is still not
locked down. Pause if splashing becomes excessive. When the vapor stream has subsided, open
the lid again and top off the liquid nitrogen in the tub, filling it to the mark on the inside wall of
the tub. If you have not already done so, insert a loaded vial or vials in the coil, and tighten and
lock the coil gate. One or two additional vials can also be put in the precooling chamber above
the coil at this time.
Shut the Freezer/Mill’s lid, engage the latch as before, and lock the lid shut by pushing the top of
the latch toward the lid. When the lid is closed and latched, further nitrogen boiling will be
visible as a stream of condensed water vapor (“fog”) from the vent in the rear of the
Freezer/Mill; this is normal. A grinding program can now be run, as outlined in Section 5.3,
Status Screen.
6.2 Loading Samples into Freezer/Mill Vials
6.21 Introduction and General Recommendations
Pick a sample typical of those you will be grinding. As a rule of thumb, the sample should be in
pieces small enough to circulate inside the vial as the impactor moves back and forth, and should
take up no more than half the volume of the vial, with the impactor in the vial. These are typical
sample sizes for the different sizes of Freezer/Mill vials:
Sample Large Vial Mid-Size Vial Small Vial Microvial
Plant Tissue, 20-40 g 5-20 g 2-5 g 100-300 mg
Bone, Muscle, etc.
Polymer 10-20 g 2-10 g 1-2 g 50-100 mg
pellet.
In practice, the optimum parameters (sample weight and size, pre-cooling time, grinding times
and number of cycles, impactor rate, etc.) are customized to match particular samples. Your own