[rhcr56]

Hello,
I am an undergrad working in a molecular biology lab, and I have a question about modifying buffers.  My cell culture media is DMEM which was ordered without sodium bicarb.  The instructions say to reconstitute with 3.7g/L of bicarb, however I am interested in making modifications in the buffering system.  First, I would like to reconstitute one batch with sodium chloride.  Can I use 3.7g/L of NaCl since it dissociates into 2 osmoles just like bicarb, or do I need to recalculate using the molar mass of NaCl?  The second batch will involve reconstituting with a concoction of Good's buffers (Tris, BES, and PIPES).  I was told the recipe needs to be 150mMol Tris, 37mMol PIPES, and 113mMol BES. I calculated how much of each buffer I need for a liter of solution, but am not sure how much to add to the DMEM solution.  Any advice?  I'm confused!  Thanks in advance.

[Jorriss]

So, what role do you think sodium bicarbonate plays in a buffer? Because I don't see why you could just switch it out for NaCl.