Rverse or normal phase

[okara]

Hello,
Can any one tell me the criteria of selecting the stationery phase by looking the structure of the compounds or
give good web site in reverse phase HPLC and why and when we use normal phase HPLC. is it a solubility
that decided to which way we go.
Please help me these basic question
Thanks

[tom jupille]

Reversed-phase is sort of the "swiss army knife" of LC techniques. It's not necessarily the best tool for all purposes, but it is adequate for many purposes. If you know nothing else about a separation, reversed-phase is the first choice; it's likely to work 90+ percent of the time.

Normal phase is the most common second choice. Particularly indicated when there is a problem with sample solubility or stability in water-containing mobile phases, or where better selectivity for isomers is needed.