Hi all, I would like to make internal solution for measurements of EPSC and IPSC in voltage clamp. I don't understand the dilution factor of CsOH and D-gluconic acid.
For both materials, it says on the bottles that they are 50% w/v. CsOh has a M.W. of 149.91 g/mol, and D-gluconic acid has a M.W. of 196.16 g/mol. I want both of them to have a final concentration of 108 mM.
How much do I take from each of them into my 50ml solution?
Thank you in advance!
Thank you Michael. I did so, added all the other ingredients and somehow, not sure why, osmolarity came out 360 (should be 290). This is why I was wondering whether I have maybe done something wrong...
Hi Yael, I also work with an internal with CsOH and gluconic acid. With gluconic acid the pH adjusts very slowly (over hours!), so you have to be careful with the first titration as the pH will most likely change. An example: my aim was 7.1, so I adjusted to 7.1 with gluconic acid, and 5-6 hours later the pH had dropped to about 6.5. So I had to titrate again, etc., adding more and more of my stock solutions and having increased osmolarity. So plan ahead and be patient :). It always took me about a day to make a complete solution with a stable pH. If I did it bit by bit and added CsOH and gluconic acid slowly, I had no problems with increased osmolarity and the right concentrations. Good luck and have a nice weekend! :)
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