retention times decreasing
Posted: Mon Jan 15, 2024 5:56 pm
I am running anion exchange chromatography in a basic eluent for determining sugars such as glucose, galactose, and agarose. I’m having issues with getting precise retention times with pure standards. They keep getting shorter over time. I investigated the possibility that it could be a carbonate issue from the mobile phase. I do nitrogen purge the mobile phase solvents (18 Mohm water and 200 mM NaOH), but this might not be sufficient to remove dissolved carbon dioxide. I cleaned the column with 2M NaOH, and the retention time increased dramatically (i.e., glucose 7 min to 9 min). Did this step remove bound carbonate to make more binding sites available? Any advice on how to get precise retention times?