Chromatography Forum

Hi, everyone!
Could anyone explain me how to prepare 0.1 M sodium acetate in acetonitrile?
The protocol calls for
solvent A: 0.1 M sodium acetate and 0.1 M acetic acid in water (pH 8 );
solvent B: 0.1 M sodium acetate and 0.1 M acetic acid in acetonitrile.

I made solvent A with no problems. Then I started with solvent B. I added acetic acid to acetonitrile. So far so good. Then I added sodium acetate. Well, it did not dissolve... at all...

Could you please anyone tell me if I am doing something wrong or if there is an error in the protocol I am using?

Ok, I'm going to ask a couple dumb questions because that's what I do:

1. Where are you getting your "protocol" from? A USP method? EPA? Somewhere else? In-house?

2. Are you SURE the protocol didn't say 0.1% sodium acetate, instead of 0.1 M? Because that would make a really big difference.

Sodium acetate - pH 8?
Some genius has left his/her footprint here

bisnettrj2,

I am using the protocol from the publication and it states 0.1 M not % sodium acetate. Is there is something wrong with 0.1M concentration. I am new to LC, for me it does not ring a bell? How do you determine what buffer concentration to use?

Astrid: I'm not in the practice of using buffers, so I've included some links below to help you out. danko is right about the first hint that something is wrong here: the pKa for acetate is 4.75, and based on the constituents of your mobile phase, you can't get to pH 8. You could adjust your pH to 8 with a base, but you're no longer within +/- one pH unit of the pKa, and therefore are not running a buffer. As for concentration, I believe (and I could be wrong because I've been wrong before and will be again) that you should probably use the lowest concentration of buffer that you can and still retain the chromatography that you desire.


http://chromatographyonline.findanalyti ... rticle.pdf

http://chromatographyonline.findanalyti ... rticle.pdf

http://chromatographyonline.findanalyti ... rticle.pdf

Also, what publication did you get this protocol from? Can you provide a link to the method?