LC mobile phase

[lwyyeung]

Dear all,

Just a curiosity, I came across a LC run, mobile phase A is 2mM ammoniun acetate (90:10, water:MeOH), and B is MeOH. What is the reason adding MeOH onto mobile phase A?

Please advise.

[JGK]

In the olden days before technology advanced and vacuum degasssers became common, the average chromatogapher would never begin gradient elution with 100% aqueous and 100% organic solvents.

Premixing some organic into the aqueous phase dramatically reduces bubble formation when the two phases are mixed and led to much betterchromatograms.

[Gaetan Glauser]

Another reason is that it will prevent or delay bacterial growth in the A line.

[Kostas Petritis]

And let's not forget the "dewetting" problem of reversed phase columns