Chromatography Forum

I searched for the answers to some quetsions but after a lot of readeing over books and on the net i just need some simple answers....

1)How and why the pH of the mobile phase affects the retention time of the compounds in Reversed phase chromatografy over C-18 Silica Gel columns?

2)how and why the temperature affects the Retention time?

3)how and why the concentration of water respect to ACN move the retention time of a solute?when i read:

"on reversed phase hplc, polar compound elute before non polar compound" i suppose it refers to the polarity of the analythe not of the mobile phase,is this correct?

Many thanks!

Questions 1 and 3 both pertain to the partition coefficient of your analyte between the mobile phase and teh stationary phase.

Question 2 has more to do with physical properties of the eluent and the speed of analyte diffusion into and out of the stationary phase.

This should help you find more of the right sections of basic chromatography primers to read (for a list, check the FAQ).