Peak tailing, Peak Fronting, Rounded Peaks in HPLC chromatogram

Peak tailing

What you expect                                   What you Got

Disease	Medicine
Active sites within the column	Test with standard test mixture. If OK add competing base or acid modifier
Wrong pH	Correct
Wrong column	Change
Void volume at inlet	May need repacking
Wrong sample solvent	Dissolve sample in mobile phase

Peak fronting

What you Expect                                What you Got    

Disease	Medicine
Column overload	See this (Retention Times are not constant)
Wrong pH	Correct
Sample solvent incompatible with mobile phase	See this (Peak Tailing)
Void volume at inlet	May need repacking
Wrong sample solvent	Dissolve sample in mobile phas

Rounded peaks

What you Expect                                  What you Got

Disease	Medicine
Detector outside linear dynamic range	Reduce sample
Gain too low	Adjust
Column overloaded	See this (retention times are not constant)
Time constants (detector, recorder) too high	Reduce
Wrong sample solvent	Dissolve sample in mobile phase

Reference:  
Prof. Dr. H.J. Chaves das Neves
Universidade Nova de Lisboa