I read with much interest the article of John Dolan in the last issue of LC.GC Europe (november 2002 vol 15 nr 11)on the hazards of adjusting gradients.

In relation to this item we encounter the following fact during our stability studies:
Although the retention times and relative retention times of the main compounds are quiet stable with gradient elution, as the stability study goes on we observe a shift in retention time for a number of compounds(often degradation compounds) and as consequence also the RRT changes. By "experience" we know that these peaks are the same as at the previous time point, but the RRT shifts. How do we deal with this ?
How does one report this phenomena in an official report. I am not aware of the critera (+/-) how I have to implement in the report. During a recent audit the auditor made this remark.
Who can help me to solve this "reporting" problem next to some technical advise in relation to the shifting of RT and RRT.

For technical advice on the retention time problems, we would need to get more info, such as column, pH, buffer, column storage etc.