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  for Metal Finishing since 1989
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DI water vs. distilled water in gold-DNA precipitation

I am trying to precipitate DNA onto gold for use with a particle gun, and the procedure calls for distilled water. In our lab we only use deionized water and reverse osmosis water. What is the difference between the three types of water, and will that affect this type of experiment?

Jess
student - Las Cruces, New Mexico, USA
2005

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Jess,
RO water is water that is forced thru a barely permeable membrane that excludes some of the ions as sodium, sulphate and etc.The quality of the wate is absolutely dependent on the membrane and the preventative maintenance done on the unit.
Distilled water is sometimes better, but not always. If it is distilled in a metal still, it will have some extra metal ions. If it is not fractionally distilled, there will be some carry over of ions that were there to start with, especially at the end of the run. sometimes some lab grades are double or tripple distilled.
DI water is totally wide open, depending on the system type and time since regeneration. This can be ulta pure at 18 Meg ohm all the way down to a cutoff light of 50K ohms.

So, unfortunately, it depends!

James Watts
- Navarre, Florida
2005