Fellow chromatographers-

Can someone tell me when I should choose normal phase vs. reverse phase HPLC? Would it be appropriate to say normal phase would be used for very polar compounds?
Thanks,
Jeff

That's right Jeff, normal phase is used for very polar compounds, because they are unretained with reversed phase. When it's possible, you should use reversed phase, because it's a lot easier to work with. With normal phase you have long equilibration times with silica, reversed phase is mostly stable after ±45 min.

Anon-
Thanks for the info.
-Jeff

Jeff,
Normal phase is used also for compounds non-soluble in water and soluble in organic solvents, then starting gradients at high concentrations of the less polar solvent and ending at high concentration of the more polar, or in isocratic mode using one solvent or a mixture.
If you want to separate very polar compounds NP can be useful, but if the components of your sample are not soluble in organic solvents then
it will not work. For hydrophilic compounds not
soluble in organic solvents you can try reversed-phase stationary phases modified with polar groups to achieve the retention of small and hydrophilic compounds, Vydac sells these columns.
I hope this can be useful.