HPLC vs UHPLC quantification

[niknen]

When trying to transfer a method from HPLC-DAD to UHPLC-DAD has anyone found that one UHPLC under- or over-estimate the concentration of sample in comparison to HPLC? or the results are very similar. The columns used in our case are different and the UHPLC DAD bears a cell with increased sensitivity.
Additional info: UHPLC autusamples is maintained at 5oC whereas HPLC one at room temperature (no possibility for temperature control)
the UHPLC column is maintained at 30 oC whereas the HPLC one at room temperature

Thank you in advance

[DR]

Assuming that adequate adjustments have been made for the different column dimensions (flow rate, injection volume, possibly sample and standard concentrations), results should be quite similar. Holding sample and column temps should make results slightly more consistent with respect to retention times and precision.

[tom jupille]

Just to check the obvious: you *did* run calibration plots on each system, right? Any instrument-to-instrument differences should cancel out.