I am working with a RI detector.(1200 agilent)
My eluant ist 800 MeOH, 100 Water, 100 0.1M ammonium acetate
I have a problem at about 3 minutes. In some chromatograms, a peak is present but in other not.
3: sample 1 first preparation
4: sample 1. second preparation
I washed the system with IPA : no peak
I made injection of 10 blanks: no peak
10 injections of the sample: peak is present.
One of my hypothesis was a change in the eluant. The reinjection of the same vial over the time is leading to the same chromatogram.