Best centrifuge tubes for use with Qiagen 500?

Dr I.M. Clark imc1001 at
Thu Jun 15 06:31:57 EST 1995

Dave Bates (dobates at wrote:
: What are people's opinions on the best tubes to precipitate the plasmid
: DNA after elution from a Qiagen tip 500.  I've been using Nalgene Oak
: Ridge tubes, both the Polycarbonate ones (which split on me too often
: for comfort - another two went today and that makes five out of the 10
: pack in the last 4 months), and the polypropylene ones in which you can
: hardly see the pellet. I don't like using these large tubes as you end
: up with a small, hard to see pellet in the bottom of a large volume
: container. Does the isopropanol stage really need to be spun at 15,000g
: to get a good pellet or can I spin it at a lower speed and use
: something like a Falcon 50ml tube at 9000g? Can you just add 35mls 100%
: Ethanol and get a nicer pellet, or is there not enough salt there?

: What is everyone's favourite.

I use the polypropylene Oakridge tubes (having had the same problems as you 
with the polycarbonate) and spin them at 30,000g (16,000rpm in a Beckman 
JA20 rotor).  This gives a very visible pellet which becomes clear after 
ethanol wash and drying, so I always mark the position of the original pellet
with a pen.  Resuspending the pellet can be a little tricky, but a quick spin
in a swing out rotor can help get everything to the bottom of the tube.
Good Luck.
Ian M. Clark
Rheumatology Research Unit,
Addenbrooke's Hospital,
Cambridge. UK.

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