Anhydrous Citric Acid USP Grade Specifications:
C6H8O7 --- 192.1
1,2,3-Propanetricarboxylic acid, 2-hydroxy-;
Citric acid CAS 77-92-9

DEFINITION
Anhydrous Citric Acid contains NLT 99.5% and NMT 100.5% of C6H8O7, calculated on the anhydrous basis.

IDENTIFICATION
A. Infrared Absorption: Dry the substance to be examined at 105C for 2 h.

ASSAY
Procedure
Sample: 0.550 g of Anhydrous Citric Acid; record weight accurately.
Analysis: Dissolve the Sample in 50 mL of water. Add 0.5 mL of phenolphthalein TS. Titrate with 1 N sodium hydroxide VS. Each mL of 1 N sodium hydroxide is equivalent to 64.03 mg of C6H8O7.
Acceptance criteria: 99.5% to 100.5% on the anhydrous basis.

Residue on Ignition: NMT 0.1%, determined on 1.0 g
Sulfate: To pass the test. --- (0.015%).
Limit of Aluminum (where it is labeled as intended for use in dialysis): To pass the test. --- (0.2 ppm).
Limit of Oxalic Acid: To pass the test.
Bacterial Endotoxins Test: The level of bacterial endotoxins is such that the requirement in the relevant dosage form monograph(s) in which Anhydrous Citric Acid is used can be met. Where the label states that Anhydrous& Citric Acid must be subjected to further processing during the preparation of injectable dosage forms, the level of bacterial endotoxins is such that the requirement in the relevant dosage form monograph(s) in which Anhydrous Citric Acid is used can be met.
Clarity of Solution: To pass the test.
Color of Solution: To pass the test.
Readily Carbonizable Substances:
Sample: 1.0 g of powdered Anhydrous Citric Acid
Analysis: Transfer the Sample to a 22-mm x 175-mm test tube previously rinsed with 10 mL of sulfuric acid and allowed to drain for 10 min. Add 10 mL of sulfuric acid, agitate until solution is complete, and immerse in a water bath at 90±1C for 60±0.5 min, keeping the level of the acid below the level of the water during the entire period. Cool the tube in running water and transfer the acid to a color-comparison tube.
Acceptance criteria: The color of the acid is not darker than that of a similar volume of Matching Fluid K in a matching tube, the tubes being observed vertically against a white background.
Sterility Tests: Where the label states that Anhydrous Citric Acid is sterile, it meets the requirements for Sterility Tests in the relevant dosage form monograph(s) in which Anhydrous Citric Acid is used.
Water Determination:
Sample: 2.0 g of Anhydrous Citric Acid
Acceptance criteria: NMT 1.0%
Packaging and Storage: Preserve in tight containers. No storage requirements specified.

Citric Acid Monohydrate USP Grade Specifications:
C6H8O7-H2O --- 210.14
1,2,3-Propanetricarboxylic acid, 2-hydroxy-, monohydrate CAS 5949-29-1

DEFINITION
Citric Acid Monohydrate contains one molecule of water of hydration. It contains NLT 99.5% and NMT 100.5% of C6H8O7, calculated on the anhydrous basis.

IDENTIFICATION
A. Infrared Absorption: Dry the substance to be examined at 105C for 2 h.

ASSAY
Procedure
Sample: 0.550 g of Citric Acid Monohydrate. Record the weight accurately.
Analysis: Dissolve the Sample in 50 mL of water and add 0.5 mL of phenolphthalein. Titrate with 1 N sodium hydroxide. Each mL of 1 N sodium hydroxide is equivalent to 64.03 mg of C6H8O7.
Acceptance criteria: 99.5% to 100.5% on the anhydrous basis.

Specifications of Citric Acid Monohydrate BP Ph Eur Grade
C6H8O7-H2O -- 210 -- CAS 5949-29-1
Citric Acid BP Monohydrate

DEFINITION
2-Hydroxypropane-1,2,3-tricarboxylic acid monohydrate.
Content: 99.5 per cent to 100.5 per cent (anhydrous substance).

CHARACTERS
Appearance: White or almost white, crystalline powder, colourless crystals or granules, efflorescent.
Solubility: Very soluble in water, freely soluble in ethanol (96 per cent).

IDENTIFICATION
First identification B, E.
Second identification A, C, D, E.
A. Dissolve 1 g in 10 ml of water. The solution is strongly acidic.
B. Infrared absorption spectrophotometry.
C. Add about 5 mg to a mixture of 1 ml of acetic anhydride and 3 ml of pyridine. A red colour develops.
D. Dissolve 0.5 g in 5 ml of water, neutralize using 1 M sodium hydroxide (about 7 ml), add 10 ml of calcium chloride solution R and heat to boiling. A white precipitate is formed.
E. Water (see Tests).

TESTS
Appearance of solution: The solution is clear and not more intensely coloured than reference.
Dissolve 2.0 g in water and dilute to 10 ml with the same solvent.
Readily carbonizable substances: To 1.0 g in a cleaned test tube add 10 ml of sulphuric acid and immediately heat the mixture in a water-bath at 90±1C for 60 min. Cool rapidly immediately afterwards. The solution is not more intensely coloured than a mixture of 1 ml of red primary solution and 9 ml of yellow primary solution.
Oxalic acid: Maximum 360 ppm, calculated as anhydrous oxalic acid.
Sulphates: Maximum 150 ppm.
Aluminium: Maximum 0.2 ppm, if intended for use in the manufacture of dialysis solutions.
Heavy metals: Maximum 10 ppm.
Water: 7.5 per cent to 9.0 per cent, determined on 0.500 g.
Sulphated ash: Maximum 0.1 per cent, determined on 1.0 g.
Bacterial endotoxins: Less than 0.5 IU/mg, if intended for use in the manufacture of parenteral dosage forms without a further appropriate procedure for the removal of bacterial endotoxins.

REQUIREMENTS
Labeling: Indicate whether it is anhydrous or hydrous.
Identification: A 1:10 aqueous solution gives positive tests for Citrate.
Assay: Not less than 99.5% and not more than 100.5% of C6H8O7, calculated on the anhydrous basis.
Lead: Not more than 0.5 mg/kg.
Oxalate: Passes test.
Readily Carbonizable: Substances Passes test.
Residue on Ignition: Not more than 0.05%.
Tridodecylamine (for solvent-extracted Citric Acid only): Not more than 0.1 mg/kg.
Water: Anhydrous: Not more than 0.5%; Monohydrate: Not more than 8.8%.

Specifications of Citric Acid Analytical Reagent
Citric Acid, Anhydrous, and Citric Acid, Monohydrate
2-Hydroxy-1,2,3-propanetricarboxylic Acid
HOCOCH2C(OH)(COOH)CH2COOH; Formula Wt. 192.13
HOCOCH2C(OH)(COOH)CH2COOH-H2O; Formula Wt. 210.14
CAS Number 77-92-9 (Anhydrous); 5949-29-1 (Monohydrate)

REQUIREMENTS
Assay: 99.5% C6H8O7; 99.0-102.0% C6H8O7-H2O min

MAXIMUM ALLOWABLE
Insoluble matter: 0.005%
Residue after ignition: 0.02%
Chloride (Cl): 0.001%
Oxalate (C2O4): Passes test
Phosphate (PO4): 0.001%
Sulfate (SO4): 0.002%
Iron (Fe): 3 ppm
Lead (Pb): 2 ppm
Substances carbonizable by hot sulfuric acid: Passes test.

MAXIMUM ALLOWABLE
Insoluble matter: 0.005%
Residue after ignition: 0.02%
Chloride (Cl): 0.001%
Oxalate (C2O4): Passes test
Phosphate (PO4): 0.001%
Sulfate (SO4): 0.002%
Iron (Fe): 3 ppm
Lead (Pb): 2 ppm
Substances carbonizable by hot sulfuric acid: Passes test.