Shifting peaks in normal phase chromatography

[jessinchrom]

I am developing a method in normal phase with ELSD. Even after stabilizing the column (Silica) for quite long time, my peaks are shifting backwards (longer retention) with nearly 1 min retention shift. the column is brand new and didnt done less than 100 injections with it with the same standards. can some one suggest what could be the possible reason and please guide me how to solve it.

[tom jupille]

It's hard to say anything useful without knowing the details of your separation:
- what column, exactly?
- what mobile phase?
- what analyte?
- what temperature (are you controlling the temperature)?
- what is "quite a long time"? How many column volumes of solvent went through the column?
- what is the approximate retention time (for example, a one-minute shift may not be significant if the retention time is 60 minutes)?
- was the shift in retention time gradual or abrupt?