Red prussiate (IUPAC name Potassium hexacyanoferrate(III), also known as red prussiate of Potash, Prussian red, and potassium ferricyanide) occurs as bright red crystals which are soluble in water. Potassium ferricyanide is manufactured by passing chlorine into a solution of potassium ferrocyanide. It is not considered to be toxic but is dangerous when heated or mixed with other chemicals.
Potassium ferricyanide is used to prepare Prussian Blue, the deep blue pigment in blue printing. It is used for the testing for ferrous ions. Potassium ferricyanide is widely used as an oxidizing agent in photographic processing to remove silver from negatives and positives, a process called dot etching. In color photograph, potassium ferricyanide is used to reduce the size of color dots without reducing their number, as a kind of manual color correction. Potassium ferricyanide is often used in physiological experiments as a means of increasing a solutions redox potential (Eo 436 mV at pH 7). Potassium ferricyanide is applied to harden iron and steel, in electroplating, dyeing wool and as a laboratory reagent. It is a mild oxidizing agent used in organic synthesis. It is associated with potassium hydroxide solution used to formulate Murakami‘s etchant, which is useful for metallographers to provide contrast between binder and carbide phases in cemented carbides. Further, it is used in many amperometric biosensors as an electron transfer agent replacing an enzyme's natural electron transfer agent such as oxygen with the enzyme glucose oxidase. It is an active ingredient in blood glucose meters used by diabetics. Potassium ferricyanide can be used as chromogenic reagent for the determination of captopril, the first orally active angiotensin converting enzyme inhibitor, which is applied for the treatment of hypertension, coronary heart disease and congestive heart failure in clinical medicine.
Potassium ferricyanide (Prussian Red) is an orange solid, It is mainly used as a pigment for staining or in photography, but also in analytical chemistry for its oxidizing properties.
Potassium ferricyanide(III) is a potassium salt widely employed as an external indicator in potassium dichromate titrations. A sensor containing potassium ferricyanide assisted enzyme electrode for estimating maltose and glucose in samples has been reported. Addition of potassium ferricyanide in the catholyte can improve the generation of power in microbial fuel cells (MFCs).
Inhalation of 2000 mg/m3 of potassium ferricyanide by rats and mice led to accumulations of ferricyanide in the blood and urine by the first day. Almost total excretion of potassium ferricyanide took place via urine by the first day after administration (STN, 1999a).
Hantson and coworkers (1996) reported that no reliable data concerning the bioavailability of potassium ferricyanide seems to exist while the bioavailability of cyanide from hexacyanoferrate, which was investigated in humans, was very poor.
[1] https://en.wikipedia.org/wiki/Potassium_ferricyanide
[2] Shi Lei Wang, Min Wang, Quan Min Li (2009) Application of potassium ferricyanide in the spectrophotometric determination of captopril, Chinese Chemical Letters, 20, 88-91
[3] M. Pandurangachar, B. E. Kumara Swamy,B. N.Chandrashekar, Ongera Gilbert, Sathish Reddy, B. S.Sherigara (2010), Electrochemical Investigations of Potassium Ferricyanide and Dopamine by 1-butyl-4-methylpyridinium tetrafluoro borate Modified Carbon Paste Electrode: A Cyclic Voltammetric Study, 5, 1187-1202
Potassium ferricyanide, also known as red potassium prussiate and red prussiate of potash, has the chemical formula C6FeK3N6 or K3[Fe(CN)6]. It is poisonous, bright red, water-soluble light-sensitive crystals that decompose when heated. The crystals are soluble in water but less so in alcohol that is used in calico printing and wool dyeing.
Potassium ferricyanide was used with ferric ammonium citrate to sensitize paper for the cyanotype process and mixed with hypo to make Farmer’s reducer which was used to reduce the density of silver-based images. This compound found various applications such as producing blueprints, photography, wood staining, wool dyeing, calico printing, etching liquid (Mercer's liquor), tempering iron and steel, electroplating, mild oxidizing agent in organic synthesis, and analytical chemistry.
It is used in many amperometric biosensors as an electron transfer agent replacing an enzyme's natural electron transfer agent with the enzyme glucose oxidase. It is a major component of Murakami's etchant for cemented carbides.
This deep red crystal was made by passing chlorine gas through a solution of potassium ferrocyanide. The oxidation of ferrocyanide yields potassium ferricyanide.Potassium ferricyanide is used as a chemical reagent and in metallurgy, photography, and pigments.
ChEBI: Potassium hexacyanoferrate(3-) is a potassium salt and a hexacyanoferrate(3-) salt.
Potassium hexacyanoferrate(III) (Potassium ferricyanide) is an alkali hexacyanoferrate. On heating, it undergoes decomposition to afford yellow-brown hexacyanoiron(III) acid. It can be prepared by the anodic oxidation of K4[Fe(CN)6].
Decomposes on strong heating to evolve
highly toxic fumes, but the compound itself has
low toxicity.
Moderately toxic by
ingestion. Not as toxic as the simple
cyanides. Mutation data reported. Explosive
reaction with ammonia, chromium trioxide
(above 196°C), sodtum nitrite + heat.
Violent reaction with Cu(NO3)2. Mixtures
with chromium trioxide + silver grains ignite with friction. When heated to
decomposition or on contact with acid or
acid fumes it emits hghly toxic fumes of
K2O and CN-. Used as a fmative in
photography, as a metal cleaner, and for
glass coatings.
It has been recrystallised repeatedly from hot water (1.3mL/g) and dried under vacuum in a desiccator.
