Trisodium citrate has the chemical formula of Na3C6H5O7. It is sometimes referred to simply as sodium citrate, though sodium citrate can refer to any of the three sodium salts of citric acid.
White, granular crystals or a white, crystalline powder; odourless; slightly deliquescent in moist air.
IP/BP/EP/USP
2.
Solubility
Freely soluble in water, practically insoluble in ethanol (95 %) and in ether.
IP/BP/EP/USP
3.
Identification
(A) The reactions of ‘Sodium salts’.
(B) The reaction A of ‘Citrates’.
(C) Upon ignition, it yields an alkaline residue which effervescences when treated with 3 N hydrochloric acid.
(A) & (B) IP/BP/EP/USP (C) USP
4.
Appearance of Solution
Solution A is clear and colourless.
IP/BP/EP
5.
Acidity or Alkalinity
(A) Not more than 0.5 ml of 0.05 M sulphuric acid or 0.1 M sodium hydroxide is required.
(B) No pink color is produced.
IP/BP/EP
6.
Arsenic
Not more than 2 ppm.
IP
7.
Heavy Metals
Not more than 10 ppm.
IP/BP/EP
8.
Chlorides
Not more than 50 ppm.
IP/BP/EP
9.
Oxalate
Not more than 300 ppm.
IP/BP/EP
10.
Sulphates
Not more than 150 ppm.
IP/BP/EP
11.
Tartrates
No crystalline precipitate is formed.
IP/USP
12.
Readily Carbonisable Substances
The solution is not more intensely coloured than reference solution YS2 or GYS2.
IP/BP/EP
13.
Water
(A) Between 11.0% w/w to 13.0% w/w.
(B) Between 10.0% w/w to 13.0% w/w.
(A) IP/BP/EP (B) USP
14.
Assay (By Titrimetry)
(A) Not less than 99.0% w/w and not more than 101.0% w/w of C6H5Na3O7, on anhydrous basis.
(B) Not less than 99.0% w/w and not more than 100.5% w/w of C6H5Na3O7, on anhydrous basis.