retention time shift using gradient

[emanuele.scollo]

I am currently experiencing RT shift when using the following gradient:
A=0.1% formic acid
B=MeOH

Time %B
0 20
9 90
11 90
12 20
14 20

the column used is a Phenomenex Kinetex C18 2.1x100 mm 2.6µ. I would be really grateful if I could get some advice on how to solve this problems.

[jiang295]

what kind of shift you are experiencing?
all of peaks shift in the same pattern,
or only early peaks shift
or some peaks shift irregularly?

I am currently experiencing RT shift when using the following gradient:
A=0.1% formic acid
B=MeOH

Time %B
0 20
9 90
11 90
12 20
14 20

the column used is a Phenomenex Kinetex C18 2.1x100 mm 2.6µ. I would be really grateful if I could get some advice on how to solve this problems.

[bisnettrj2]

Try lengthening the re-equilibration time at 80%A at the end of your gradient (try 10 minutes instead of 2 minutes to start). If your RT problem is remedied, you weren't re-equilibrating long enough. If you post more details, we can give better advice.

System type?
Flow rate?
Gradient dwell volume?
And the answer to jiang's question above...

[emanuele.scollo]

I lengthened the equilibration time and the retention time are conistent now thanks for the help