filter-sterilized MilliQ water for PCR?

Koen De Smet k.desmet at
Thu Sep 18 06:27:44 EST 1997

Hiranya Roychowdhury wrote:
> At 01:24 AM 9/17/97 -0700, Jun-Ichi Aikawa wrote:
> >Clontech recommended to use filter-sterilized MilliQ water for PCR instead
> >of autoclaved water, because autoclave can introduce salts. Does anyone use
> >filter-sterilized water for PCR? Do I need to worry about its nuclease or
> >protease contamination?
> >
> Where do these salts come
> from in autoclaved water, unless they are already present in it an/or some
> other solution boils over in the autoclave and contaminates the distilled
> water sitting beside it. 

I 'have been told' (this is very scientific!) that salts/minerals will leach in MilliQ 
from the glass that the bottles are made of, and that MilliQ water should therefore 
always be kept in sterile plastic bottles (without autoclaving). Having said this, I 
have for a very long time used water from glass bottles for PCR and other molecular 
biology techniques, without having had problems that I could link to the glass. 

(I have even used MilliRO water for succesful PCR, a grade that is known to contain all 
kinds of rubbish. But I stopped that when I amplified DNA from an environmental 

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 De Smet

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___												                 																												___
___     Department of Medical Microbiology																		___
___     Imperial College School of Medicine at St Mary's    ___
___     London W2 1PG																																		     ___
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