Agilent x Waters

What size column, and what flow rate on each system? I'm assuming the same column is used on both systems.

Yes, its is the same column in both system. I´m using a 1,2 mL/min and a Inertsil Ph column from GL Sciences, 

Inertsil Ph-3 HPLC Column, 5 µm, 250 x 4.0 mm

Hey Julia,

It sounds like it is a difference in system volumes and the delay volume it takes for the gradient to reach the column. Maybe you have different types of pumps (binary versus quaternary) or maybe different samplers (flow-through needle versus fixed loop). These hardware differences create volume differences which result in different retention times.

Are you running a gradient? If isocratic, the elution time should be based mostly on the flow rate, assuming the same solvent composition. If a gradient, the comments from kbusch will apply.

It is a gradient!! Manu thanks for reply

It is gradient, many thanks for reply!