Investigations of properties and binding forms of cadmium and nickel in protein extracts by ultra-/diafiltration, photometry and atomic absorption spectrometry

A combination of a special ultrafiltration procedure with photometry and atomic absorption spectrometry for application in the speciation analysis of protein containing solutions is described, allowing not only the determination of qualitative distribution patterns of metal species but also the quantitative characterization of metal species. According to these investigations, exemplified by cadmium and nickel species in protein extracts of bean seeds, it is demonstrated how to use this method. The results show that cadium and nickel have completely different binding mechanisms in these seeds. Furthermore, these investigations lead to the result that the application of membrane separation techniques in speciation analysis is not limited to the separation into molecular weight ranges only. Much more, they are useful techniques in combination with detection methods to obtain information about binding strength and the complexing ability of different matrices to bind heavy metals. © 1994 Springer-Verlag.