Nadine,
Amino acid analysis should be the best method. I do vapor
phase acid hydrolysis,followed by derivatization with AccQTag,which contain
sodium borate. Separation is done on a C18 column. Metal chelators are
present throughout the procedure. I think that ,whatever holds the metal
will be destroyed by the acid hydrolysis,and picked up by the chelotor
after hydrolysis. Anyway chelation should not be very good under extreme
acid conditions.
I selected AccQTag,because hardly anything interferes with it. The
presence of extraneous non-protein material could give rise to unexpected
peaks,but I cannot foresee any major problem.
"Ritter, Nadine"
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Does anyone know of a method to determine protein concentration in
materials
that are chelated to heavy metals? Colormetric methods have been tried, but
exhibit high imprecision, and I have concerns about the accuracy of results
coming from a standard curve made with protein not chelated to metal.
Amino
acid analysis was attempted but the heavy metal appeared to interfere with
the pre-column derivatization. An extinction coefficient is not yet
determined, so UV is not very useful yet. Ideas?
Nadine Ritter, Ph.D.
Director, Analytical Services
BioReliance Corp.
nritter@bioreliance.com
301-610-2587
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