C6H8O7 192.12

1,2,3-Propanetricarboxylic acid,2-hydroxy-.
Citric acid [77-92-9].

Monohydrate 210.14 [5949-29-1].

Packaging and storage— Preserve in tight containers.

Labeling— Label it to indicate whether it is anhydrous or hydrous.

Identification— Asolution responds to the tests for Citrate á191ñ.

Water,Method Iá921ñ: not more than 0.5%(anhydrous form)and not more than 8.8%(hydrous form).

Readily carbonizable substances— Transfer 1.0g,powdered for the test,to a 22-×175-mm test tube previously rinsed with 10mLof sulfuric acid TSand allowed to drain for 10minutes.Add 10mLof sulfuric acid TS,agitate until solution is complete,and immerse in a water bath at 90±1for 60±0.5minutes,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:the color of the acid is not darker than that of a similar volume of Matching Fluid K(see Color and Achromicity á631ñ)in a matching tube,the tubes being observed vertically against a white background.

Residue on ignition á281ñ: not more than 0.05%.

Sulfate— To 10mLof a solution (1in 100)add 1mLof barium chloride TSto which has been added 1drop of hydrochloric acid:no turbidity is produced.

Arsenic,Method Iá211ñ: 3ppm.

Heavy metals á231ñ: 0.001%.

Limit of oxalate— Neutralize 10mLof a solution (1in 10)with 6Nammonium hydroxide,add 5drops of 3Nhydrochloric acid,cool,and add 2mLof calcium chloride TS:no turbidity is produced.

Organic volatile impurities,Method IVá467ñ: meets the requirements.

Assay— Place about 3g of Citric Acid in a tared flask,and weigh accurately.Dissolve in 40mLof water,add phenolphthalein TS,and titrate with 1Nsodium hydroxide VS.Each mLof 1Nsodium hydroxide is equivalent to 64.04mg of C6H8O7.USP28

Expert Committee:(EMC)Excipients:Monograph Content

USP28–NF23Page 483

Phone Number:1-301-816-8262