RT Variation

[sharma]

We are experiencing Retention time problem in waters vs Agilent system.

When injecting sample on waters RT is 15 min but with same sample/column/ mobile phase RT on Agilent system is about 18-19 min. Can anyone explain the reason?

Regards

[paulw]

The first thing I would do is check the flow rate no each instrument and make sure they are both accurate. This can be done by checking the void, or even just setting the instrument to your flow rate and collecting mobile phase for 10 minutes in a graduated cylinder.

If you are performing a gradient run (or you are pump mixing mobile phase), it may be a question of the difference in the mixing of the two instruments. Does one instrument have a large excess amount of tubing (though 3 minutes large for that to be the issue).

[tom jupille]

Isocratic or gradient? If gradient, what are the respective dwell volumes on those systems?

[sharma]

Yes we have checked the flow rate it has % error of 0.4%. The RT variation is observed both with isocratic and gradient modes.

Regards

[rrm1987]

can you check the tubing length(i.e., volume) between column outlet and detector inlet.If it varies likely Rt also varies.Try i hope this could be the possible reason.

[DJ]

Column dimensions? Flow rate?