Name: Iron Oxides
CAS No: Iron oxides [1332-37-2] (a) Iron oxide black [1317-61-9] (b) Iron oxide red [1309-37-1] (c) Iron oxide yellow [51274-00-1] (monohydrate); [20344- 49-4] (hydrate)
None adopted.
(a) Iron oxide black: Bayferrox 306; black magnetic oxide; black oxide, precipitated; black rouge; CI 77499; E172; ethiops iron; ferric ferrous oxide; ferrosoferric oxide; Ferroxide 78P; Ferroxide 88P; iron oxide; iron (II, III) oxide; iron oxides (FeO); magnetite; Mapico Black EC; pigment black 11; Sicovit B80; Sicovit B85; triiron tetraoxide. (b) Iron oxide red: anhydrous ferric oxide; anhydrous iron (III) oxide; Bayferrox 105M; CI 77491; diiron trioxide; E172; Ferroxide 212P; Ferroxide 226P; hematite; pigment red 101; red ferric oxide; Sicovit R30. (c) Iron oxide yellow monohydrate: E172; hydrated ferric oxide; iron (III) oxide monohydrate, yellow; pigment yellow 42; yellow ferric oxide. Iron (III) oxide hydrated: Bayferrox 920Z; CI 77492; ferric hydroxide; ferric hydroxide oxide; ferric hydrate; ferric oxide hydrated; Ferroxide 510P; iron hydrate; iron hydroxide; iron hydroxide oxide; Mapico Yellow EC; Sicovit Y10; yellow ochre; yellow iron oxide.
Iron oxides [1332-37-2] (a) Iron oxide black [1317-61-9] (b) Iron oxide red [1309-37-1] (c) Iron oxide yellow [51274-00-1] (monohydrate); [20344- 49-4] (hydrate)
(a) Fe3O4 231.54 (b) Fe2O3 159.70 (c) Fe2O3H2O 177.70 (monohydrate); FeHO2 88.85 (hydrate)
Iron oxides are defined as inorganic compounds consisting of any one of or combinations of synthetically prepared iron oxides, including the hydrated forms.
Iron oxides are widely used in cosmetics, foods, and pharmaceutical applications as colorants and UV absorbers.(1–3) As inorganic colorants they are becoming of increasing importance as a result of the limitations affecting some synthetic organic dyestuffs. However, iron oxides also have restrictions in some countries on the quantities that may be consumed, and technically their use is restricted because of their limited color range and their abrasiveness.
Iron oxides occur as yellow, red, black, or brown powder. The color depends on the particle size and shape, and crystal structure
See Section 18.
Density 5.1 g/cm3 for iron oxide black (Fe3O4); 5.2 g/cm3 for iron oxide red (Fe2O3); 4.1 g/cm3 for iron oxide yellow (Fe2O3H2O). Melting point 15658C for iron oxide red (Fe2O3) Solubility Soluble in mineral acids; insoluble in water.
Iron oxides should be stored in well-closed containers in a cool, dry place.
Iron oxides have been reported to make hard gelatin capsules brittle at higher temperatures when the residual moisture is 11–12%. This factor affects the use of iron oxides for coloring hard gelatin capsules, and will limit the amount that can be incorporated into the gelatin material
Three main manufacturing processes are currently applied for iron oxide pigments:(4) (a) Solid-state reactions (red, black and brown): calcination of black or yellow iron oxides to red iron oxide; thermal decomposition of ferrous sulfate. (b) Precipitation process (red, orange, yellow and black): treatment of ferrous sulfate solutions with alkali and oxidation. The Penniman–Zoph process uses ferrous sulfate, alkali, iron powder and air or oxygen. (c) Laux process or aniline process (red, yellow, and black): reduction of nitrobenzene to aniline with iron.
Iron oxides are widely used in cosmetics, foods, and oral and topical pharmaceutical applications. They are generally regarded as nontoxic and nonirritant excipients. The use of iron oxide colorants is limited in some countries, such as the USA, to a maximum ingestion of 5 mg of elemental iron per day. LD50 (mouse, IP): 5.4 g/kg(5) LD50 (rat, IP): 5.5 g/kg
Observe normal precautions appropriate to the circumstances and quantity of the material handled. In the UK, the workplace exposure limits for iron oxide fumes (as Fe) are 5 mg/m3 long-term (8-hour TWA) and 10 mg/m3 short-term.(6
Observe normal precautions appropriate to the circumstances and quantity of the material handled. In the UK, the workplace exposure limits for iron oxide fumes (as Fe) are 5 mg/m3 long-term (8-hour TWA) and 10 mg/m3 short-term.(6
Accepted for use as a food additive in Europe. Included in nonparenteral medicines licensed in many countries including Japan, UK, and USA.
The EINECS number for iron oxide black (Fe3O4) is 215-277-5. The EINECS number for iron oxide red (Fe2O3) is 215-168-2. The EINECS number for iron oxide yellow (Fe2O3H2O) is 257-098-5. Although iron oxides are not included in any pharmacopeias, the Joint FAO/WHO Expert Committee on Food Additives has issued specifications for iron oxide; see Table I.(7) Specifications for iron oxide black,(8) iron oxide red,(9) and iron oxide yellow monohydrate(10) are included in the Japanese Pharmaceutical Excipients (JPE); see Table II.