Chromatography Forum

Why only methanol and acetonitrile were used during initial trails of method development..why not other solvents in HPLC? Why most of the trails start with Reverse phase? Why not normal phase in HPLC?

Most of the compounds that most people want to analyze can be separated by RP.

Most separations can be achieved using methanol or ACN.

So, that means you start with the technique (reversed phase) and the mobile phases (MeOH and ACN) that gives you the best chance to accomplish your separation goals as quickly as possible.

there's nothing to stop you setting up a normal phase method. In fact if I did some literature searching and found that the compounds of interest were more often run in normal phase conditions, that is exactly what I'd do. Also, if looking at my analytes, they were obviously very, very polar, I wouldn't attempt to set up a reverse phase method. I'd think about Hilic, normal phase, or GC after derivatisation.

The only concerns about normal phase are things like pump-seal compatibilities with the solvents you need, extra fume-extraction, etc.

Having said all that, reverse phase is so easy to get going, and so reliable, that if it's possible to do something by reverse phase, I would.