KI 166.00

Potassium iodide.
Potassium iodide [7681-11-0].

Packaging and storage— Preserve in well-closed containers.

Identification— Asolution of it meets the requirements of the tests for Potassium á191ñand for Iodide á191ñ.

Alkalinity— Dissolve 1.0g in 10mLof water,and add 0.1mLof 0.1Nsulfuric acid and 1drop of phenolphthalein TS:no color is produced.

Loss on drying á731ñ— Dry it at 105for 4hours:it loses not more than 1.0%of its weight.

Iodate— Dissolve 1.1g in sufficient ammonia-and carbon dioxide-free water to obtain 10mLof solution,and transfer to a color-comparison tube.Add 1mLof starch TSand 0.25mLof 1.0Nsulfuric acid,mix,and compare the color with that of a control containing,in a similar volume,100mg of Potassium Iodide,1mLof standard iodate solution [prepare by diluting 1mLof potassium iodate solution (1in 2500)with water to 100mL],1mLof starch TS,and 0.25mLof 1.0Nsulfuric acid.Any color produced in the solution of the test specimen does not exceed that in the control:not more than 4µg per g is found.

Limit of nitrate,nitrite,and ammonia— To a solution of 1g in 5mLof water contained in a test tube of about 40-mLcapacity add 5mLof 1Nsodium hydroxide and about 200mg of aluminum wire.Insert a pledget of purified cotton in the upper portion of the test tube,and place a piece of moistened red litmus paper over the mouth of the tube.Heat the test tube and its contents in a steam bath for 15minutes:no blue coloration of the paper is discernible.

Thiosulfate and barium— Dissolve 0.5g in 10mLof ammonia-and carbon dioxide-free water,and add 2drops of 2Nsulfuric acid:no turbidity develops within 1minute.

Heavy metals á231ñ— Dissolve 2.0g in 25mLof water:the limit is 0.001%.

Organic volatile impurities,Method Iá467ñ: meets the requirements.

Assay— Dissolve about 500mg of Potassium Iodide,accurately weighed,in about 10mLof water,and add 35mLof hydrochloric acid.Titrate with 0.05Mpotassium iodate VSuntil the dark brown solution which is produced becomes pale brown.Add 2to 3drops of amaranth TS,and continue the titration slowly until the red color just changes to yellow.Each mLof 0.05Mpotassium iodate is equivalent to 16.60mg of KI.

Expert Committee:(PA7)Pharmaceutical Analysis 7

USP28–NF23Page 1595

Phone Number:1-301-816-8394