Autoclaving Reagents

John Watson watson_j at
Tue Nov 26 15:03:32 EST 1996

Rick Bright wrote:
> Okay, I am new so please don't laugh.  I made my solutions today for a
> new protocol and my advisor suggested autoclaving each stock solution.
> I encountered a few problems.
> 1) In making my 1 Molar EDTA solution, the EDTA did not go into
> solution, is this normal, if so, how do I get it to go into solution.
> Even after autoclaving it is not in solution.  This may be correct, so
> please let me know if it is.

 Adjust the pH to 8.  It may take awhile on the stirplate to go into solution.

> 2) In making my 6 Molar NaCl solution, it did not all go into solution.
> During the autoclave process, it spewed all inside the autoclave.  So, I
> need to know how to make it all go into solution and how I should
> autoclave to prevent the explosion.

I have never made 6 M NaCl.  5 M and 4 M, but not 6 M.

> 3) I made two Tris-HCl solutions, one pH 7.6, the other pH 8.0.  This
> worked well, except during the autoclave procedure, the bottle
> containing the pH 7.6 split around the bottom.  The entire bottom was
> cut all around the bottle, so the top just lifted off and the solution
> went happily down the drain.

An easy thing to do is to autoclave bottles of liquid in an autoclave pan (polypropylene?) 
that has an inch or so of water in the bottom -- just enough to cover the bottom of the 
bottles.  This helps prevent superheating of the glassware.  Use good bottles, too.  I 
prefer Pyrex glass over the cheap borosilicate stuff.

> 4) The other solutions, 1 M MgCl2 and 1 M KCl all went well through the
> autoclave.
> You are wondering how I autoclaved.  I used a large industrial autoclave
> on wet cycle for 20 minutes at 121C.  I made sure the caps were just
> sitting on top of the bottle, not screwed on at all.  The bottles were
> placed directly on the rack with plenty of space surrounding them.

See number 3, above.

John Watson
Bristol-Myers Squibb Co.
watson_j at
"If you're not part of the solution, you're part of the precipitate."

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