Citric acid

Prepared at the 49th JECFA (1997)
superseding specifications prepared at the 46th JECFA (1996),
published in FNP 52 Addendum 4 (1996)

SYNONYMS

INS No. 330

DEFINITION

Chemical name

2-hydroxy-1,2,3-propanetricarboxylic acid

C.A.S. number

77-92-9 (anhydrous)
5949-29-1 (monohydrate)

Chemical formula

C₆H₈O₇ (anhydrous)
C₆H₈O₇. H₂O (monohydrate)

Structural formula

Figure Anhydrous

Figure Monohydrate

Formula weight

192.13 (anhydrous)
210.14 (monohydrate)

Assay

Not less than 99.5% and not more than 100.5% on the anhydrous basis

DESCRIPTION

White or colourless, odourless, crystalline solid. The monohydrate form effloresces in dry air

FUNCTIONAL USES

Synergist for antioxidants, sequestrant, acidity regulator, flavouring agent

CHARACTERISTICS

IDENTIFICATION

Solubility

Very soluble in water; freely soluble in ethanol; slightly soluble in ether

Positive Test for citrate

Passes test

PURITY

Water

Anhydrous: Not more than 0.5% (Karl Fischer method)
Monohydrate: Not less than 7.5% and not more than 8.8% (Karl Fischer method)

Sulphated ash

Not more than 0.05%

Lead

Not more than 0.5 mg/kg
Prepare a sample solution as directed for organic compounds in the Limit Test and determine the lead content by atomic absorption spectrometry

Oxalate

Passes test
See description under TESTS

Readily carbonizable substances

Passes test
See description under TESTS

TESTS

PURITY TESTS

Oxalate

Neutralize 10 ml of a 10% solution of the sample with dilute ammonia TS. Add 5 drops of dilute acetic acid TS, cool and add 2 ml of calcium chloride TS. No turbidity should be produced.

Readily carbonizable substances

Heat 1.0 g of sample with 10 ml of 98% sulfuric acid in a water bath at 90±1° for 60 min. No colour darker than Matching Fluid K (25°) should be produced (not more than 0.5 absorbance units at 470 nm in a 10 mm cell).

METHOD OF ASSAY

Weigh, to the nearest mg, 2.5 g of the sample and place in a tared flask. Dissolve in 40 ml of water and titrate with IN sodium hydroxide, using phenolphthalein TS as the indicator. Each ml of IN sodium hydroxide is equivalent to 64.04 mg of C₆H₈O₇.

SYNONYMS	INS No. 330
DEFINITION
Chemical name	2-hydroxy-1,2,3-propanetricarboxylic acid
C.A.S. number	77-92-9 (anhydrous) 5949-29-1 (monohydrate)
Chemical formula	C₆H₈O₇ (anhydrous) C₆H₈O₇. H₂O (monohydrate)
Structural formula	Figure Anhydrous
Structural formula	Figure Monohydrate
Formula weight	192.13 (anhydrous) 210.14 (monohydrate)
Assay	Not less than 99.5% and not more than 100.5% on the anhydrous basis
DESCRIPTION	White or colourless, odourless, crystalline solid. The monohydrate form effloresces in dry air
FUNCTIONAL USES	Synergist for antioxidants, sequestrant, acidity regulator, flavouring agent
CHARACTERISTICS
IDENTIFICATION
Solubility	Very soluble in water; freely soluble in ethanol; slightly soluble in ether
Positive Test for citrate	Passes test
PURITY
Water	Anhydrous: Not more than 0.5% (Karl Fischer method) Monohydrate: Not less than 7.5% and not more than 8.8% (Karl Fischer method)
Sulphated ash	Not more than 0.05%
Lead	Not more than 0.5 mg/kg Prepare a sample solution as directed for organic compounds in the Limit Test and determine the lead content by atomic absorption spectrometry
Oxalate	Passes test See description under TESTS
Readily carbonizable substances
	Passes test See description under TESTS
TESTS
PURITY TESTS
Oxalate	Neutralize 10 ml of a 10% solution of the sample with dilute ammonia TS. Add 5 drops of dilute acetic acid TS, cool and add 2 ml of calcium chloride TS. No turbidity should be produced.
Readily carbonizable substances
	Heat 1.0 g of sample with 10 ml of 98% sulfuric acid in a water bath at 90±1° for 60 min. No colour darker than Matching Fluid K (25°) should be produced (not more than 0.5 absorbance units at 470 nm in a 10 mm cell).
METHOD OF ASSAY	Weigh, to the nearest mg, 2.5 g of the sample and place in a tared flask. Dissolve in 40 ml of water and titrate with IN sodium hydroxide, using phenolphthalein TS as the indicator. Each ml of IN sodium hydroxide is equivalent to 64.04 mg of C₆H₈O₇.