[Protein-analysis] how to evaluate the recovery of renaturation of protein from inclusion body

[subberry]

My protein si a scFv,without activity.

After dissolved in 6M guanidine containing B-mercaptoethanol, and
purified by IMAC with 100mM imidazole, the protein concentration should
be determined, and the cd and absorbtion spectrum should be measure,
but by doing this i just found the guanidine and imidazole have great
interference. Anybody can tell me beside BCA,which method can
determined protein concentration in 6M guanidine /
B-mercaptoethanol/imidazole.

And the second question:how to evaluate the recovery of protein
refolded from inclusion body, determination of refolded and soluble
protein concentration and get the ratio of C of refolded and of
unfolded?