APTS Purity / Related Subs testing
I'm having some trouble separating out impurites for qualifying APTS chromophore for a saccharide labeling kit.We've found some material (a different brand than our normal supplier) with a strange UV-Vis absorbance profile, but can't seem to find a good solvent/buffer/column combination that separates the impurities (positional isomers?) out from one another. It just flies through the RP columns we have... it all dumps out right after the void in one big fat peak, to nobody's surprise (its super electron-dense). The HILIC BEH-Amide (2.1x100 @ 1.7um) columns don't seem to want to resolve the different compounds, either. We get a barely noticeable bump (Empower won't integrate it separately) with the BEH-Amide running 70/30 Aqueous/ACN.Any ideas?