Berlin-blue reaction

Haemosiderin is also an iron-protein complex, assumed to be formed from ferritin. In the case of iron overload in the body, more haemosiderin than ferritin is formed, which is then stored in the intracellular space. Haemosiderin can be demonstrated biochemically using the Berlin blue reaction, (see chapters 5.5.2 and 31.17)... 

In order to gain an antiserum for ferritin studies, Wohler and Schonlau (W7) injected rabbits with a 0.05 % isotonic solution of ferritin (20 % iron) at pH 7.2. Injections were made every fourth day, and 0.5, 1.0, 2.0, and (twice) 2.0 mg were given subcutaneously. The titer which was thus obtained was 1 500. If this antiserum was used in ImEl against separate sera with a content of at least 100 ng % ferritin, lines of precipitation could be stained with Berlin blue reaction. Ferritin shows a line which comes near Pi-globulin. A positive Ouchterlony test was obtained with most patients suffering from hepatitis epidemica or from liver cirrhosis. 

Tile Berlin blue reaction shows arbutin as a blue (--413), the Millons reagent as a yellow zone (- C) in sample 1. In sample 3, in the II, range of arbutin two minor blue (->13) and yellow ( C) zones are detectable. 

Turbidity-causing solids are mostly proteins as well as oxidized and condensed polyphenols. Furthermore, multivalent metal ions can cause discoloration and sediments. Wine clarification is usually achieved by precipitation reactions, filtration or centrifugation. In blue-fining the excess metal ions which are responsible for metal-induced cloudiness (iron, copper and zinc) are precipitated by precisely calculated amounts of potassium ferrocyanide. In this process, soluble Berlin blue is formed first,... 

Fe + may also be characterized by the reaction it gives with the hexacyano-ferrate(II) anion [Fe(CN)6]" formerly called the ferrocyanide ion. A deep blue precipitate called Berlin blue or Prussian blue forms. It is interesting to notice that the ferrocyanide ion is a complex itself. The structure of ferric hexacyanoferrate-(II), namely, Fe4[Fe(SCN)6]3, has been ascribed to Prussian blue. 

Cyanide iron blues can be prepared by several methods. The most common one is the indirect, two-step process. In the first step, a white precipitate (Berlin white), is produced by the reaction of sodium, potassium, or ammonium ferrocyanide and ferrous sulfate ... 

The industrial production of Prussian blue is based on the reaction in aqueous solution of sodium hexacyanoferrate(n), Na4Fe(CN)6, with iron(n) sulfate, FeS04-7H20 in the presence of an ammonium salt, which results initially in the formation of the colourless insoluble iron(n) hexa-cyanoferrate(n) (Berlin white). Prussian blue is generated by subsequent oxidation with a dichromate or chlorate. 

At high anodic potentials Prussian blue converts to its fully oxidized form as is clearly seen in cyclic voltammograms due to the presence of the corresponding set of peaks (Fig. 13.2). The fully oxidized redox state is denoted as Berlin green or in some cases as Prussian yellow . Since the presence of alkali metal ions is doubtful in the Prussian blue redox state, the most probable mechanism for charge compensation in Berlin green/Prussian blue redox activity is the entrapment of anions in the course of oxidative reaction. The complete equation is ... 

Electroreflectance spectroscopy has been successfully applied to numerous other systems such as oxide films or adsorbed dyes. It is most useful when the observed features can be related to specific electronic transitions. As an example we mention the reactions of a film of Prussian Blue adsorbed on gold or platinum. Prussian Blue can be oxidized to Berlin Green, or reduced to Prussian White. The appearance of the products gives rise to characteristic features in the electroreflectance spectra [11]. 

Iron blue [14038-43-8], C.I. Pigment Blue 27 77510 (soluble blue is C.I. Pigment Blue 27 77520), was discovered in 1704 by Diesbach in Berlin by a precipitation reaction, and can be regarded as the oldest synthetic coordination compound. Milori was the first to produce it as a pigment on an industrial scale in the early nineteenth century [3.178],... 

The redox chemistry of the Prussian blue family (Table 7) has attracted considerable attention. The generation of thin films of Prussian blue has led to studies of its mediation in electron transfer reactions and of the electrochemical processes involved in its deposition and redox reactions. This work has been spurred by its electrochromic properties which have been used in prototype electronic display devices based, for example, on Prussian blue modified Sn02 electrodes. A recent review deals with the electrochemistry of electrodes modified by depositing thin films of PB and related compounds on them. Interestingly, true Prussian blue is somewhat difficult to process and modem iron blue pigments such as Milori blue are derived from the oxidation of Berlin white Fe(NH4)2[Fe(CN)6] to give iron(III) ammonium ferrocyanides. 

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