HPLC

High pressure forces a solvent (mobile phase) through closed columns containing fine particles that give high resolution seperations

Diffusion is 100x slower in liquids then in gases; the diameter of an open column would be too great to traverse. In a packed column a solute molecule doesn't have to go far to encounter stationary phase

performance

reverse phase HPLC

normal phase HPLC

(remember NOnpolar = NOrmal phase)

Small particles size provide more uniform flow deceasing A.

Smaller particles require less distance to diffuse, decreasing C

Small particle size leads to:
1) high plate number
2) shorter run time
3) and lower detection limits

BUT

you need higher pressures to force mobile phase through the column

As you increase the temp of the column you are decreasing the viscosity of the solvent therefore reducing the retention time, and required pressure, which will improve resolution.

However you degrade the stationary phase and therefore the lifetime of the column

-though sensitive, this detector responds only to a few analytes (those that fluoresce).
-derivatization can be performed to covalently attach fluorescent groups to analyte