Updated July 5, 1990
Srini Ramachandra
The HETO vacuum concentrator can be used to remove trace amounts of volatile liquids, (e. g. ethanol while drying DNA pellets obtained from plasmid/cosmid preps and phage lysates). The unit consists of: a centrifuge that can hold up to 60 1.5ml-eppendorf tubes, a vacuum pump, and the Model CT 60e cooling trap. Both the centrifuge and the cooling trap are connected to the vacuum pump. The cooling trap should always be used, and can be left on continuously until the trap is drained.
Draining the cooling trap:
(First: Leave a note on the HETO that the trap is turned off for draining, so that no one will try to use it.)
To drain the trap, turn off the cooling trap and allow any frozen liquids in the trap to liquify (the time for this may vary, depending on the volume frozen, you may place warm water into the stainless steel container to speed the thawing). When the thaw is complete, open the drain valve in the front of the cooling trap and collect the liquid waste in a beaker. Close the drain valve. Turn the cooling trap on, and wait an hour before use. Try to drain the trap after each use unless the concentrator was used for drying down already nearly dry DNA pellets. If DNA pelleted samples are being dried down, first drain as much of the supernatant from the pelleted samples as possible before using the HETO.
Note: Frequently check the oil level of the pump through the sight glass. The oil level should be at the middle of the sight glass when the pump is off. Otherwise open the oil fill plug and add enough oil (VTR VO 19 vacuum fluid or AHL synthetic oil, Cat. # S 4601).
1. Check to be sure the cooling trap is on. Turn the vacuum pump on. The switch is at the back of the orange pump.
2. Open the vent behind the centrifuge to atmosphere. The vent is the white plastic knob at the end of the black rubber hose. The broad wing of the white knob should be facing up for the vent to open to atmosphere.
3. Lift the lid of the centrifuge and place the eppendorf tubes with their tops open. Balance the tubes.
4. Close the lid by pulling the steel latch down.
5. Turn the centrifuge on, wait till the rotor reaches maximum speed and slowly open the vacuum vent to the centrifuge chamber. The small wing of the white knob should line up with that of the black rubber hose.
To stop the run:
6. Slowly open the vent to atmosphere as in stepe# 2, turn the centrifuge off, wait for the rotor to come to a complete stop (listen to the latch click), and then lift the lid.
7. Remove the tubes slowly and cap them immediately. Turn off the vacuum pump. If large volumes were involved, drain the cooling trap as decribed above.
Notes: Dry DNA pellets for approximately 10 minutes. Normally it is not necessary to use the heater. The heater can be turned on during the run to speed the process. To dry down oligos, run the HETO for 4 to 8 hours with the heater turned on.