Retention time shift on 1290 HPLC in both directions


I would like to seek advice regarding our problem with retention time shift we get for our standards on our 1290 Infinity system. Retention time shift is in both directions to right and left and is around 0.3 to 1 % of total retention within 20 injections, which we consider as a problem as normally we observe very minimal retention shift of around 0.03 % within 400 injections. At fist we observed leaks from different ports on both switching valves in autosampler and in column compartment. All fittings were tightened and no further leaks were observed, also instrument passed all leak tests.

Do you have any ideas what could be the reason for this shift?

We know that the column is not an issue as we don't observe any retention time shift when we use column on a different system.

Best Regards

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