Calcium ferrocyanide
13821-08-4 · 906D36VLZG · BAZQCHGUTMBXBU-UHFFFAOYSA-N · Calcium ferrocyanide · Calcium hexacyanoferrate · calcium hexacyanoferrate(II) · Dicalcium hexacyanoferrate · DICALCIUM HEXACYANOFERRATE(4-) · dicalcium;iron(2+);hexacyanide · E 538 · Ferrate(4), hexakis(cyanokappaC), calcium (1:2), (OC611) · FERRATE(4-), HEXACYANO-, DICALCIUM · Ferrate(4-), hexakis(cyano-.kappa.C)-, calcium (1:2), (OC-6-11)- · FERRATE(4-), HEXAKIS(CYANO-C)-, CALCIUM (1:2), (OC-6-11)- · Ferrate(4-), hexakis(cyano-kappaC)-, calcium (1:2), (OC-6-11)- · HEXACYANOFERRATE OF CALCIUM · INS NO.538 · INS-538 · Yellow prussiate of lime · Yellow prussiate of limeCalcium hexacyanoferrate · E538 · 538 · dicalcium;iron(2+);hexacyanide · Calcium ferrocyanide · Calcium ferrocyanide · Calciumferrocyanid · Calciumhexacyanoferraat(II) · Ferocianură de calciu · FEROKYANID VÁPENATÝ · Ferrocianeto de cálcio · Ferrocianuro cálcico · Ferrocianuro di calcio · Ferrocyanure de calcium · Ferrokyanid vápenatý · Ferroċjanur tal-kalċju · Hexakyanoželeznatan vápenatý · Kalcija ferocianīds · kalcijev ferocianid · Kalcijev ferocijanid · Kalcio ferocianidas · KALCIUM-FERRO-CIANID · Kalcium-vas(II)-cianid · Kalciumferrocyanid · Kalsiumferrosyanidi · Kaltsiumferrotsüaniid · KALTSIUMHEKSATSÜANOFERRAAT(II) · Żelazocyjanek wapnia · Σιδηροκυανιούχο ασβέστιο · Калциев фероцианидE number E538INS 538CAS 13821-08-4
Listed as an anticaking agent by Codex.
Listed as anticaking agents (Codex)
- Codex Alimentarius: Anticaking agent — CXS 192-1995 Table One, INS 538
Calcium ferrocyanide is an anticaking agent for salt. Despite the name, the cyanide groups are tightly bound in an iron complex, the ferrocyanide ion also found in the pigment Prussian blue.
Where it is and isn’t permitted
| Jurisdiction | Status | Scope and limits | Citation |
|---|---|---|---|
| Australia and New Zealand | No listed food uses foundThis site has not matched this substance to any food use on this jurisdiction’s list of authorised food additives. A food additive may be used only in foods that list names. Flavourings, enzymes, processing aids and added nutrients are regulated separately and do not appear on it. | ||
| Canada | No listing matchedHealth Canada’s lists name additives without E or INS numbers, so this site matches them by exact name. A substance listed there under a name this site does not recognise has no row here. | ||
| European Union | Permitted, with conditions | 2 food categories highest permitted level 20 mg/kg Permitted as a member of Ferrocyanides. ML = 20 mg/kg. Note 1: The additives may be added individually or in combination. Show every food category
| Regulation (EC) No 1333/2008, Annex II, as amended by (EU) No 1129/2011and 1 further provisionretrieved 2026-10-18 |
| Great Britain | Permitted, with conditions | 2 food categories highest permitted level 20 mg/kg or mg/l Authorised under E 535-538, Ferrocyanides. ML = 20. Note (1): The additives may be added individually or in combination. Note (57): The maximum level is expressed as anhydrous potassium ferrocyanide. Show every food category
| Assimilated Regulation (EC) No 1333/2008, Annex II (as at 28 June 2024), under E 535-538and 1 further provisionretrieved 2026-10-18 |
| Japan | Permitted, with conditions | Designated additive: Appended Table 1, item 356, フェロシアン化物（フェロシアン化カリウム（別名ヘキサシアノ鉄（Ⅱ）酸カリウム）、フェロシアン化カルシウム（別名ヘキサシアノ鉄（Ⅱ）酸カルシウム）及びフェロシアン化ナトリウム（別名ヘキサシアノ鉄（Ⅱ）酸ナトリウム）に限る。） (“Ferrocyanides (li …Designated additive: Appended Table 1, item 356, フェロシアン化物（フェロシアン化カリウム（別名ヘキサシアノ鉄（Ⅱ）酸カリウム）、フェロシアン化カルシウム（別名ヘキサシアノ鉄（Ⅱ）酸カルシウム）及びフェロシアン化ナトリウム（別名ヘキサシアノ鉄（Ⅱ）酸ナトリウム）に限る。） (“Ferrocyanides (limited to Potassium Ferrocyanide (Potassium Hexacyanoferrate(II)), Calcium Ferrocyanide (Calcium Hexacyanoferrate(II)), and Sodium Ferrocyanide (Sodium Hexacyanoferrate(II)))” in the unofficial English translation; listed member: Calcium Ferrocyanide (Calcium Hexacyanoferrate(II))). Standards for use — Specifications and Standards for Foods, Food Additives, etc. (MHW Notification No. 370 of 1959), Part II (Food Additives), F (Standards for use), entry フェロシアン化カルシウム: (1) [may be used only in the foods stated] “フェロシアン化カルシウムは、食塩以外の食品に使用してはならない。” (2) [sets maximum levels of use for the foods stated; sets a combined limit where it is used together with the additives stated] “フェロシアン化カルシウムの使用量は、無水フェロシアン化ナトリウムとして、食塩1kgにつき0.020g以下でなければならない。ただし、フェロシアン化カリウム若しくはフェロシアン化ナトリウムの1種又は2種と併用する場合にあっては、それぞれの使用量の和が無水フェロシアン化ナトリウムとして、食塩1kgにつき0.020g以下でなければならない。” The Japanese is the standard as published. There is no official English translation of the Notification; the English in square brackets is this site’s description of what each sentence does, not a translation of the foods or the levels. Compositional specifications for this additive, in the same Notification, are not imported and are not shown here; nor are the general rules in F 添加物一般, which apply to every additive. | Regulations for Enforcement of the Food Sanitation Act (MHW Ordinance No. 23 of 1948), Appended Table 1retrieved 2026-10-18 |
| South Korea | Permitted, with conditions | Designated food additive: Standards and Specifications for Food Additives, Part III, 1. …Designated food additive: Standards and Specifications for Food Additives, Part III, 1. 일반식품첨가물 (general food additives), 페로시안화칼슘 (“Calcium Ferrocyanide”, the English the Code prints beside it). Main use (주용도) of 페로시안화칼슘: 고결방지제. Standard for use (사용기준) of 페로시안화칼슘: (1) [may be used only for the purpose or in the food the sentence states; sets a limit on the amount used] “페로시안화칼슘은 식염(천일염 제외)에 한하여 사용하여야 한다. 페로시안화칼슘의 사용량은 페로시안이온으로서 식염 1kg에 대하여 0.010g 이하(페로시안화칼륨 또는 페로시안화나트륨과 병용할 때에는 각각의 사용량의 합계가 페로시안이온으로서 식염 1kg에 대하여 0.010g 이하)이어야 한다.” The Korean is the standard as published. There is no official English translation of the current Code (the English version on MFDS’s website is the 2020 edition and has no legal effect); the English in square brackets is this site’s description of what each sentence does, not a translation of the foods or the levels. Compositional specifications (Part IV) are not imported, nor are the general standards in Part II, which apply to every additive. | Standards and Specifications for Food Additives (식품첨가물의 기준 및 규격), MFDS Notification, Part III (Standards for use, by item)retrieved 2026-10-18 |
| United States | Not listedDoes not appear on this jurisdiction’s permitted list. That is not the same as being prohibited. | ||
| Codex Alimentarius | Permitted, with conditions | 3 food categories highest permitted level 20 mg/kg Show every food category and its notes
| CXS 192-1995 Table One, INS 538and 2 further provisionsretrieved 2026-09-07 |
How much is permitted
A listing usually limits the quantity as well as the food. Only one of the forms that takes is a figure: quantum satis and good manufacturing practice permit the amount the technological effect requires and no more, which is a limit rather than the absence of one. Figures below are the range across every food category this page is listed in, and categories differ between regulators — see how much is permitted.
| European Union | 20 mg/kg | 2 numeric limit |
|---|---|---|
| Great Britain | 20 mg/kg | 2 numeric limit |
| Japan | — | 1 no quantity stated |
| South Korea | — | 1 no quantity stated |
| Codex Alimentarius | 14 mg/kg – 20 mg/kg | 3 numeric limit |
What it is made from
Produced synthetically from a ferrocyanide salt and a calcium source. It is used at a few parts per million in salt, enough to change how the crystals grow.
- Vegan
- Vegetarian
Compare other additives on the dietary indexes.
- CAS registry number
- 13821-08-4
- InChIKey
- BAZQCHGUTMBXBU-UHFFFAOYSA-N
- PubChem
- CID 166920
How the EU defines it
The legal specification an additive must meet to be sold as this E number in the EU — what it is, how it may be made, and the purity it must reach. From Commission Regulation (EU) No 231/2012.
E 538 Calcium ferrocyanide
Synonyms: Yellow prussiate of lime; Calcium hexacyanoferrate
Assay, identification and purity criteria
Description and assay
- Einecs
- 215-476-7
- Chemical name
- Calcium ferrocyanide
- Chemical formula
- Ca₂Fe(CN)₆ · 12H₂O
- Molecular weight
- 508,3
- Assay
- Content not less than 99,0 %
- Description
- Yellow crystals or crystalline powder
Identification
- Test for calcium
- Passes test
- Test for ferrocyanide
- Passes test
Purity criteria
- Free moisture
- Not more than 1,0 %
- Water insoluble matter
- Not more than 0,03 %
- Chloride
- Not more than 0,2 %
- Sulphate
- Not more than 0,1 %
- Free cyanide
- Not detectable
- Ferricyanide
- Not detectable
- Lead
- Not more than 5 mg/kg
Every name it appears under
49 recorded names. A label may use any of them.
E number
- E538
INS number
- 538
CAS registry number
- 13821-08-4
As it appears in regulation
- Calcium ferrocyanide
Other names
- 906D36VLZG
- BAZQCHGUTMBXBU-UHFFFAOYSA-N
- Calcium ferrocyanide
- Calcium hexacyanoferrate
- calcium hexacyanoferrate(II)
- Dicalcium hexacyanoferrate
- DICALCIUM HEXACYANOFERRATE(4-)
- dicalcium;iron(2+);hexacyanide
- E 538
- Ferrate(4), hexakis(cyanokappaC), calcium (1:2), (OC611)
- FERRATE(4-), HEXACYANO-, DICALCIUM
- Ferrate(4-), hexakis(cyano-.kappa.C)-, calcium (1:2), (OC-6-11)-
- FERRATE(4-), HEXAKIS(CYANO-C)-, CALCIUM (1:2), (OC-6-11)-
- Ferrate(4-), hexakis(cyano-kappaC)-, calcium (1:2), (OC-6-11)-
- HEXACYANOFERRATE OF CALCIUM
- INS NO.538
- INS-538
- Yellow prussiate of lime
- Yellow prussiate of limeCalcium hexacyanoferrate
Systematic names
- dicalcium;iron(2+);hexacyanide
Hazard reference values
The two committees set different figures. EFSA's acceptable daily intake is 0.03 mg/kg bw/day (2018); JECFA's is 0.025 mg/kg bw/day (1974). An acceptable daily intake is a reference value set by a committee, not a threshold above which harm begins. The lower figure is not a finding that the other body was wrong: the two work to different terms of reference, on their own timetables, and sometimes from different data. This site states both and chooses between them nowhere. See where the two committees differ.
Evidence and how bodies read it
What assessing bodies concluded
Each conclusion is paraphrased in the body's own framing, from the published opinion linked beneath it. Where bodies differ, both stand; this site does not adjudicate between them or add a view of its own.
EFSA 2018
The ANS Panel found no concern for genotoxicity or carcinogenicity for sodium, potassium and calcium ferrocyanide (E 535–E 538) and, based on kidney effects in a two-year rat study, established a group ADI of 0.03 mg/kg bw/day expressed as ferrocyanide ion. It concluded they are of no safety concern at the current authorised use as salt substitutes and use levels.
Common questions
Assembled from what is above, in the words the questions are usually asked in. Each answer is the same statement the relevant section makes, with the same citations behind it.
- What is E 538?
- E 538 is Calcium ferrocyanide. Calcium ferrocyanide is an anticaking agent for salt. Despite the name, the cyanide groups are tightly bound in an iron complex, the ferrocyanide ion also found in the pigment Prussian blue.
- What is Calcium ferrocyanide used for in food?
- It is listed as an anticaking agent — the role Codex assigns it. This page shows every function each regulator records, with the citation for each.
- Where is Calcium ferrocyanide permitted?
- Of the seven regulators this site reads, the EU, Great Britain, Japan, South Korea and the Codex standard permit it. Each permission is for named foods at named levels, not a blanket one; the table on this page gives them with citations.
- Is Calcium ferrocyanide vegan?
- Yes. Calcium ferrocyanide is not derived from animals, and is suitable for vegetarians. This page says what it is made from and how.
Sources for this page
- eu retrieved 2026-10-18
- gb retrieved 2026-10-18
- jp retrieved 2026-10-18
- kr retrieved 2026-10-18
- gsfa retrieved 2026-09-07
- euspecs retrieved 2026-10-18
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