filter-sterilized MilliQ water for PCR?

Bryan L. Ford fordb at bcc.orst.edu
Thu Sep 18 14:30:24 EST 1997


Koen De Smet wrote:
> 

> I would suspect (again a very scientific statement I can't back up) that the amounts of
> minerals released from glass would be minimal, compared to the millimolar range of salt
> and MgCl2 that is used in common buffers.
> 
> Anyway, could anybody confirm or deny if minerals leach from glass, and if these
> quantities may at any stage become high enough to affect enzymes?

> I would suspect (again a very scientific statement I can't back up) that the amounts of
> minerals released from glass would be minimal, compared to the millimolar range of salt
> and MgCl2 that is used in common buffers.
> 
> Anyway, could anybody confirm or deny if minerals leach from glass, and if these
> quantities may at any stage become high enough to affect enzymes?

Koen:

It would be good to have some analytical chemists'and some enzymologists
input on this, but in lieu of that here are a few accumulated factoids
and hearsay.

Perhaps you have seen or read that borosilicate glasses (eg. Pyrex,
Kimax) are  known to release substantial amounts of minerals, especially
in the presence of phosphoric acid and even phosphate buffers or in the
presence of strong bases. If you don't want silicates and borates in
your cultures, reactions or analyses then it may be wiser to use flint
glass (good except in the presence of fluorides) or appropriate
plastics. It seems very likely that autoclave conditions would greatly
accelerate any attack on glassware (for example, look closely at
frequently autoclaved glass)-- but whether the resulting "salts" would
influence downstream molecular biology reactions seems quite speculative
at this point. Certainly solid silicates are known to bind DNA under a
variety of conditions, but as yet I have not seen any documented
evidence that dissolved silicates interact with DNA.  I doubt that
molecular biologists (outside of the area of plant cell culture where
boron and silicates can be critical nutrients) have to worry about this
issue much. Just in case I usually avoid placing sensitive reagents in
borosilicate glassware. This is not to say that I would be completely
confident with plastics either, and certainly autoclaving solutions in
plastic would be exploratory basic research for me.

-Bryan




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