My protein stays in solution with a high imidazole content (250mM imidazole) however, when analysing the results, imidazole is not within the buffer range, or rather, the program cannot compute the density for the buffer composition. Has anyone run AUC with imidazole in the buffer composition?
You should be careful the imidazole may saturate the absorbance detector, and it will be see by the interference detector. As a rule I would no run AUC with imidazole.
I can't really run my AUC without imidazole.. because even at 200mM imidazole, my proteins crash.. I did notice a rather noisy result from my interference data..
Interference detection should work, though any system may have its own peculiarities and challenges. In any case, you should try to match the volumes in the reference and sample sectors as closely as possible, in order to avoid any signal contribution from unmatched buffer components.
The noise in your data may be mainly due to a rather low protein concentration. If possible, analyse 1-2 mg/mL in 12 mm cells.
For density/viscosity, I recommend a search on the RASMB site.
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