Pyrrolidine and TEA

[Koen Hollebekkers]

I have a, maybe for some people, simple question. How should I adjust a TEA buffer and a pyrrolidine buffer to the appropriate pH. Let say pH 11. I also want to order pyrrolidine, but which compound do I have to order, just pyrrolidine or Methylpyrrolidine?

[Uwe Neue]

It works the same way as it works for acid-based buffers. You take acetic acid at a fixed concentration, then you add sodium hydroxide or sodium acetate to make a buffer. If you need an MS compatible buffer, you use ammonia or ammonium acetate instead.

For a buffer based on a base, you start with a solution of a known concentration of the base, for example pyrrolidine, and you add the appropriate acid to get to the pH that you would like. You can use HCl or other acids for non-MS methods, and acetic or formic acid for MS-compatible methods.

[Koen Hollebekkers]

Thanks Uwe,

I want to b sure that I prepare the buffer in the right way. Too many times separation fails just by the inappropriate preparation of buffers by annalists

[Mark Tracy]

While you are titrating the pH, weigh the water, the base, and measure the exact volume of acid. In the future, just make it by weight and the pH will be right. (Assuming that your ingredients are well behaved and you are not trying to titrate too far from the pKa.)