I'm trying to separate chromium III and VI using a carbamate column and tetraethylammoniumhydrogensulfat as ion pair reagent. So far all my attempts have been unsuccessful. All I get is one peak. If I inject Cr III I get one peak (rt app. 2,5 min, 212 nm) and if I inject Cr VI a smaller peak appears with same rt but at different wavelength (359,3 nm). Mixture of Cr III and VI reveals nothing new, just same kind of peaks as mentioned above. I have changed pH, MeOH/water ratio and the ion pair concentration but nothing seems to help. Any ideas ?