Ammonium Bicarbonate Buffer

[AMR]

I am using Ammonium Bicarbonate pH 8.0 mobile phase for an assay and I am having a few problems with the stability of the pH. Does anyone know of any tricks to keep the the pH stable? Are there any preocedures during preparation that may help?

[tom jupille]

Degas the water before you make the buffer, and then make sure you use a CO2 trap on the reservoir.

[Mark Tracy]

Tom's remark about degassing prior to mixing is important. Degassing ammonium bicarbonate buffer will change its pH.

[Uwe Neue]

Unfortunately, the pH of an ammonium bicarbonate "buffer" in this pH range or at lower pH will change anyway. The formation of CO2 appears to be slow. The pH of the buffer is unstable with time, even if it is degassed properly to start with.

[HW Mueller]

On top of this, the buffer is not so hot at pH = 8.