Chromatography Forum

Well, Victor overtake me in the explanation of my believes.

My conception of buffers is have some acid or base that keeps reproducible the ionic strenght of the eluent - besides the analytes are ionizable or not.

Anyway, as everything, you have some bias in your work. I do it for 20 years, it works, I keep doing it.

I think the easiest way to say it is; if the mobile phase has ANYTHING in it, with the exception of water and solvent.............its buffered.

The rushing devil struck again, I wanted to add enough H+ to increase the concentration (if there were no buffering) 10x, not by 10 mole. Thus one would have to add 0.09 mol H+, thus: 0.01M + 0.09 mol = 0.1M, the pH would go from 2 to 1 in absence of buffering..... it doesn´t, of course, since there is buffering due to water (this assumes H+ concentration = H+ activity, for simplicity).

Rafael, one can control the ionic strength with neutral salts, without pH control, done very often.

KC, one should use the word buffering only when the changes in mol which appear in solution do not correspond to the mol added.

A buffer is a buffer if it buffers the pH (i.e. if I throw in a tiny amount of acid or base into the buffer the pH does not change). If it doesn't, it isn't.

A salt solution (NaCl) in water is not a buffer. Nor is a solution of NaAc.

For rest , call them "Modifiers"

JM