Prussian blue cysteine with

A particular interest for clinical applications was a possibility for detection of dopamine by its oxidation on nickel [19], cobalt [65], and osmium [66] hexacyanofer-ates. Except for oxidation of dopamine, cobalt and osmium hexacyanoferrates were active in oxidation of epinephrine and norepinephrine. For clinical analysis it is also important to carry out the detection of morphine on cobalt [67] and ferric [68] hexacyanoferrates, as well as the detection of oxidizable amino acids (cystein, methionine) by manganous [69] and ruthenium [70] hexacyanoferrate-modified electrodes. In general, oxidation of thiols was first shown for Prussian blue [71] and nickel hexacyanoferrate [72], This approach has been used for the detection of thiols in rat striatum microdialysate [73], Alternatively, the detection of thiocholine with Prussian blue was employed for pesticide determination in acetylcholine-esterase test [74],... 

In order to decrease the overpotential for cysteine oxidation in cysteine-containing peptides, graphite-epoxy resin or carbon paste electrodes with immobilized cobalt phthalocyanine have been employed in HPLC systems [53,87-89]. Glassy carbon electrodes modified with a mixed-valence ruthenium(I V,III) oxide film stabilized by cyano cross-links [61,62], indium ferricyanide [63], or a Prussian blue film [64], and a bismuth(V)-doped lead dioxide Pb02 film on gold [65] have also been used for detection following HPLC separation. In addition, a carbon fiber modified with a nfixed-valence ruthenium(IV,III) oxide film stabilized by cyano cross-links has been used in CE [46]. 

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