HNO3 63.01

Nitric acid.
Nitric acid [7697-37-2].

Packaging and storage— Preserve in tight containers.

Clarity and color— Mix it in its original container,and transfer 10mLto a 20-×150-mm test tube.Compare with water in a similar test tube:the liquids are equally clear and free from suspended matter,and,when viewed transversely by transmitted light,exhibit no apparent difference in color.

Identification— It responds to the tests for Nitrate á191ñ.

Residue on ignition á281ñ— To 70mL(100g)in a tared crucible add 2drops of sulfuric acid,and evaporate to dryness.Ignite for 15minutes:the weight of the residue does not exceed 0.5mg (5ppm).

Chloride á221ñ— A35-mL(50-g)portion shows no more chloride than corresponds to 35µLof 0.020Nhydrochloric acid (0.5ppm).

Sulfate á221ñ— Add about 10mg of sodium carbonate to 28mLof Nitric Acid.Evaporate to dryness,dissolve in a mixture of 4mLof water and 1mLof dilute hydrochloric acid (1in 20),and filter if necessary.Wash with two 2-mLportions of water,dilute with water to 10mL,and add 1mLof barium chloride TS.Observe 10minutes after adding the barium chloride:any turbidity produced is not greater than that produced by 40µLof 0.020Nsulfuric acid in an equal volume of solution containing the quantities of reagents used in the test (1ppm).

Iron á241ñ— Evaporate 35mL(50g)to dryness,dissolve the residue in 2mLof hydrochloric acid,and dilute with water to 47mL:the limit is 0.2ppm.

Heavy metals,Method Iá231ñ— To 70mL(100g)in a 250-mLbeaker add about 10mg of sodium carbonate,and evaporate on a steam bath to dryness.Add 25mLof water:the limit is 0.2ppm.

Assay— Weigh accurately about 2mLof Nitric Acid in a tared,glass-stoppered conical flask,and add 25mLof water.Add methyl red TS,and titrate with 1Nsodium hydroxide VS.Each mLof 1Nsodium hydroxide is equivalent to 63.01mg of HNO3.

Expert Committee:(EMC)Excipients:Monograph Content

USP28–NF23Page 3041

Phone Number:1-301-816-8379