Zur Analytik von Harnstoff-Melamin-Formaldehyd-Harzen

Summary A method is described for the distinction between urea-formaldehyde and melamine-formaldehyde resins by precipitating the melamine derivates with picric acid. The analysis of this precipitation by urease-decomposition gives information whether urea and melamine are condensed with formaldehyde together or whether the investigated resin is only a mixture of an urea-formaldehyde and a melamine-formaldehyde resin.Moreover, it is possible to prove the formation of cocondensates of urea, melamine, and formaldehyde during the three-component condensation by combination of these two methods.     

Surface-electrochemistry of ferritin adsorbed on 8-mercaptooctanoic acid-modified gold electrodes

Ferritin adsorbs on gold electrodes modified with a layer of 8-mercaptooctanoic acid. Cyclic voltammetry indicates the reduction of the ferritin layer at negative potentials followed by an anodic process in the return scan. However, a second cycle reveals that the latter signal is the anodic branch of a new electrochemical couple rather than the anodic branch of adsorbed ferritin. Control experiments including stirring the scan solution, electrochemical induction of iron release, and varying the scan rate strongly support the hypothesis that a dissolved iron species is released when ferritin is reduced, but its oxidized form adsorbs onto the SAM-modified electrode surface.