Chromatography Forum

Hey guys! I'm an undergrad doing research at Clemson. I'm trying to separate 2 almost structurally similar compounds (2-bromoisobutyryl bromide and 1-bromocarbonyl-1-methylethyl acetate) using a fast acid column but the 2 peaks co-elute at about 2.8 mins. My mobile phase is a 5mM sulfuric acid in HPLC water at a flow rate of .5mL/min and my column temperature in 40 C....Is there something different I can do or try?? Please let me know!
I could not attach the link for the structures of the 2 compounds(2-bromoisobutyryl bromide and 1-bromocarbonyl-1-methylethyl acetate) but they can found on the sigma-aldrich's website: http://www.sigmaaldrich.com/european-export.html

Thanks very much!

Aren't you hydrolyzing your analytes during the analysis?

Maybe try to lower the temperature of your column (at 15-20 C) or use another column (what column are you using now?).

You didn't give a lot of details, but from the description "fast acid column" and the mobile phase, I surmise that you're using a PS-DVB-sulfonate cation exchange resin in the hydrogen form. You didn't give column dimensions or flow rate, so I have no idea about the dead time of the column (i.e., 2.8 minutes may represent no retention at all).

If 2.8 minutes is at or close to the dead time, then this column is unsuitable for your analysis and you will have to go back to "square one" and a more conventional HILIC or reversed-phase column. If 2.8 minutes represents reasonable retention (i.e., if your dead time is less than a minute), then dropping the temperature or increasing the sulfuric acid concentration may help (but no guarantees!).

And, like bhuvfe, I'd be concerned about stability in a low-pH mobile phase.