I am trying to make a sodium-free bath solution for patching and the literature is not clear on how to make NMDG-methanesulfonate solutions. I tried to make one using NMDG and methanesulfonic acid but the pH ended up being extremely low, and I couldn't get the pH up to 7.4 with NMDG alone. Is this a standalone compound? It is not listed anywhere on the Sigma website or other chemical manufacturers.
Rheanna,
Let me give you and example of what we do in the lab. Let's make 1 liter of a 100 mM NMG+ solution at pH 7.4:
1.) In a beaker with ~900 ml of water, add 19.521 g of NMG. This amount correspond to 100 mmoles of NMG.
2) Add 2.38 g (10 mmoles) of HEPES. Also, CaOH as needed.
3) Add ~5.8 ml of MeSO3 acid (be careful). This correspond to about 90 mmoles of acid. Tip: you can add a little less, about 5.5 ml, and then add the rest as you titrate the solution to pH 7.4.
4) at this point, you should have your solution ready to be added with water to reached a final volume of 1 liter. After this, filter your solution with a 0.22 um filter to remove any insoluble particles.
Good luck.
are you not able to simply titrate in methanesulfonic acid to the NMDG powder dissolved in water until the pH is correct? Could you use NMDG-Cl instead? This can be done with NMDG and titrated with conc HCl. I also made NMDG-Gluconate a few times by titrating NMDG with gluconic acid and that seemed to work fine.
Rheanna,
Let me give you and example of what we do in the lab. Let's make 1 liter of a 100 mM NMG+ solution at pH 7.4:
1.) In a beaker with ~900 ml of water, add 19.521 g of NMG. This amount correspond to 100 mmoles of NMG.
2) Add 2.38 g (10 mmoles) of HEPES. Also, CaOH as needed.
3) Add ~5.8 ml of MeSO3 acid (be careful). This correspond to about 90 mmoles of acid. Tip: you can add a little less, about 5.5 ml, and then add the rest as you titrate the solution to pH 7.4.
4) at this point, you should have your solution ready to be added with water to reached a final volume of 1 liter. After this, filter your solution with a 0.22 um filter to remove any insoluble particles.
Good luck.
Thanks Jonathan and Carlos!
I guess I wasn't familiar with the concept of "titrating" the MeSO3 into the NMDG. I just added the calculated molar amount without monitoring pH. I obviously went way over the tipping point which drove the pH down much too low. I will now try making the solution while adding the acid slowly and monitoring pH. Thanks again!
p.s. I feel stupid now, but I just noticed that I had my NMDG molecular weight off by 100 g/mol (I had it as 95.21) - so this would also be a huge reason why the pH ended up so low. I might not have figured that out unless you had given that example, Carlos! So thanks!
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