6875 Freezer/Mill
Page 23 of 42
SPEX® SamplePrep LLC
DEC 2015
6.2.3 Loading a Sample into a Vial at Room Temperature
Most Freezer/Mill samples do not have to be kept cold all the time, and can be loaded at room
temperature. To load a vial, first assemble it halfway by pushing an end-plug into a center
cylinder. Add the sample and impactor to the vial, and close it with the other end-plug. Shake
the vial to make sure the impactor has room to move back and forth.
6.2.4 Loading a Cold Sample into a Vial and Keeping it Cold
Some samples must be kept cold, such as plant or animal tissue being prepared for RNA
extraction. When a sample is cold, and must be kept cold throughout the grinding process, the
loading procedure is more elaborate.
Assemble the center cylinder and blunt end plug, as in 6.2.3, then chill the end plug and about an
inch of the cylinder in a shallow liquid nitrogen bath. The vial rack that comes with the 6875
Freezer/Mill can be placed in an insulated container and used to hold the vials upright during
chilling. At the same time, chill the impactor separately. As soon as the submerged end of the
vial is chilled, drop in the cold sample and then the chilled impactor.
(Always wear insulated
gloves when handling chilled vial components directly!)
Now carefully insert the other end plug,
still warm, into the warm end of the cylinder. The vial can now be carefully placed in the mill, or
submerged in a liquid nitrogen bath outside the mill, as long as care is taken not to let the sample
touch the warm end plug before it has cooled down.
CAUTION: Never force an end plug (warm or cold) into a polycarbonate cylinder (warm or cold.
Polycarbonate shrinks when chilled, and can crack if stressed. If the cylinder has
cooled to the point that the end plug fit is too tight, allow the cylinder to warm up
before inserting the end plug.
6.2.5 Loading a Very Small Sample into a Vial and Keeping it Cold
A variant of the loading technique in Section 6.2.4 can be used to grind very small samples with
the open pre-chilled vial upright. Place the sample on the chilled end plug and add a small
amount of fluid such as an extraction medium or water. The frozen fluid will bulk up the sample
enough so it will circulate in the vial during grinding. To speed up this process, some users first
prepare small “ice cubes” of the sample frozen together with 0.5 ml to 1 ml of fluid.
6.3 Loading a Vial into the Freezer/Mill
Before loading a vial or vials in the 6875 Freezer/Mill, put on cryogenic gloves. Unlatch and lift
the lid of the mill, and open the coil gate. If Small or Mid-Size vials are being used, make sure the
proper Adapter is in the coil. Pick up the vial(s) with a gloved hand or an Extractor/Vial Opener
and insert the vial(s) into the coil. Close the coil gate and tighten it against the vials(s) by turning
the gate handle clockwise, but do not overtighten the gate. Lock the gate by folding down the
handle.
Additional vials can be placed in the precooling basket and carefully immersed in the LN tub on
the right hand side (the end which faces the coil gate) with the basket handle against the tub