I was hoping someone out there would be willing to share their current method for analyzing their cannabinoid profile with me. I have one I frequently use, but I am using a new system and it is not nearly the same, despite my best efforts to maintain all of my previous conditions. It is an Agilent infinity series.
I’m currently using two mobile phases: 5 mM Ammonium Formate, water, 1% FA and 0.1% FA in ACN for phase 2. 50/50 all the way, I am not ramping up, but believe that may be a part of the issue. I usually run UV at 228 nm but my last run I tried 200-280, but when I did it kept giving me report which detected NOTHING at all.
At 50% water / 50% organic solvent it could be that your compound is being retained on the column for longer and eluting after your method injection cycle time is up and the detector may be set to automatically turn off after cycle is finished.
What are the column dimensions?
If your mobile phase composition, gradient, detector, column are the same from instrument to instrument, should be getting very close results (assuming both instruments work fine).
So should I up the amount of solvent? I am having the DAD go for 28 minutes, I figured that should have been plenty of time. However, my DAD report comes out looking like y=ax^n kind of curved line.
Run pure solvent through the column and watch the DAD signal to see if any retained peaks come off the column. After 30 mins of this, Increase the ACN composition of your mobile phase and try some injections (maybe do 75% ACN 25% water) 50/50 is too much water, will take longer for compounds to elute. My method I used 86% Methanol / 14% water, and follow an injection with a 3 minute extrusion with pure organic solvent to try and remove any strongly retaining junk from the column