Storage of Milli Q Water - (Sep/26/2013 )

hi. How much time can I storage milli Q water on a Pyrex Bottle?

Make sure the pyrex is clean, add MilliQ water and then autoclave it.  As long as you maintain a seal on the bottle, you could potentially store it indefinitely. Even when I am using my Autoclaved MilliQ water as a stock, I like to frequently rinse, add new MilliQ water and autoclave (once every two or so weeks). A clean Pyrex bottle should not leach.

CO2 in the air will gradually acidify milliQ water. For most applications, this can be ignored, since any buffer, even at very low concentrations, will drive the pH. If you really want the water pure, I would avoid the autoclave.

Just out of curiosity, why would you avoid the autoclave?

MilliQ water has extremely high purity, and exposure to even a metal container will dissolve significant (relative to its purity) amounts of metal. An autoclave will leave a wide variety of contaminants. In biology, those are perhaps ignorable for many applications, but in other disciplines, such as seminconductor manufacturing, no one would dream of letting their water anywhere near an autoclave. If you are doing trace metal analysis, then you should probably be similarly skeptical. DNA contamination is probably more of a problem. Have you looked inside your autoclave recently? Sterile, yes, but pure, not so much.

Thanks for the help