Tailing high and increases with injection volume

[rgamage]

A question about tailing: This is for assay testing. Normal concentration and injection volume (5uL) gives 2.119 tailing. When injection amount changed by injection volume (uL) it gives inj.vol/tailing values 2/1.556, 3/1.772, 5/2.119, 7/2.316, 10/2.617. Clearly at normal condition tailing is too high, when injection amount increased tailing also increases. Is this not acceptable (for a good reliable assay method)? What are the risks? Does this variation suggest column overloading?

[tom jupille]

Overloading is one possibility. The other is the "strong solvent effect" if the diluent is stronger than the mobile phase (ideally,the diluent should be the same or weaker).

What column dimensions?