Chapter 4: Using Your RapidVap
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20
Original instructions
The unique performance of the RapidVap N
2
is dependent upon the proper balance
of heat, gas flow and vortexing action. If the proper balance is not established, it is
possible to damage or lose a portion of the sample. Therefore, if you are
unfamiliar with the RapidVap N
2
or are attempting a new protocol, it may me
helpful to make a trial run that is void of the sample you are attempting to
concentrate.
Determine if the sample which is to be processed will be allowed to go to dryness
or whether the evaporation is to cease prior to dryness. If the process should not
go to dryness, the proper sample tubes must be selected to allow the desired
amount of solvent to remain in the tubes. Sample tubes are available for various
end point volumes. Refer to
Appendix D: Accessories
for available sample tubes.
Any style ground glass tube may be used if the sample is to go to dryness,
however, flat bottom tubes evaporate the quickest.
Glassware Selection and Speed Setting
Guidelines
The speed at which the sample block should oscillate is dependent on the sample
tube size and the sample volume. Generally, the tube should be no more than half
full. The faster the speed, the higher the sample will vortex giving a maximum
surface area and therefore a maximum evaporation rate. However, if the speed is
too fast, samples will raise above the top of the tube and be lost. Smaller tubes can
be run faster than larger tubes. The following table gives recommended safe
speeds for tubes loaded with water.
Experimentation
with the specific sample may
determine faster speeds. When setting the speed, keep in mind that the sample will
raise up slightly in the tube when vacuum is applied to the chamber of the vacuum
model.
GLASS VIALS USED IN THE RAPIDVAP SHOULD BE OF
THE STYLE THAT DO NOT HAVE THE BEAD OR LIP ON
THE TOP EDGE. IF VIALS WITH BEADS ARE USED, THE
BEADS COULD HIT EACH OTHER AND BREAK THE
GLASS.
N
