Quenstion-Do you add the sodium pyruvate into the DMEM or 1640 meduim？ - (Mar/16/2012 )

Do you add the sodium pyruvate into the DMEM or 1640 meduim which is bought from company? someone tell me the sodium pyruvate will be degrade 50% two weeks. So if my meduim stay more than two weeks, the 200mM sodium pyruvate should be added.

Are you sure you (or the person who you spoke to) aren't thinking of L-glutamine? L-glutamine is an unstable amino acid and so is often added to media just before use (media stored in fridge, L-glu stocks at -20C).

I'm pretty sure that sodium pyruvate is stable in the fridge for at least a year or so.

I buy medium from company Nacalai tesque with L-Glutamine and sodium pyruvate already added.
they said if properly stored (2-8) it will be good till expiration date 1-2013 ????

The media will be fine for that long, madelingirly, but you will definitely have to supplement with extra L-glu after about a month in the fridge.

what does this mean
leelee

So I shall added l-glutamine to any fresh new bottle I have from the company, as these bottles already stored in the main company???
Or you mean after opening for example???

Good question, regarding adding it to new media that has L-glu already in it. I'm not really sure what to advise you on that, I hope someone else has the answer.

I buy my media without L-glutamine, then buy the L-glu separately and store it in smaller aliquots at -20C and add it to each bottle of media as I need it.

We used to make our own L-glu containing media from powder , and in that case I would usually top up with more L-glu after about 1-2 months of storage at 2-8C.

Leelee is correct, the L-glut does degrade to form ammonia (IIRC). You can just add more l-glutamine, but this should not be repeated more than two times, to prevent build up of the ammonium in the solution.