Urea, chemical structure, molecular formula, Reference Standards
»Urea contains not less than 99.0percent and not more than 100.5percent of CH4N2O.
Packaging and storage
Preserve in well-closed containers.Store at 25,excursions permitted between 15and 30.
Where it is intended for use in preparing injectable dosage forms,the label states that it is sterile or must be subjected to further processing during the preparation of injectable dosage forms.
USP Reference standards á11ñ
USP Endotoxin RS.
Heat about 500mg in a test tube:it liquefies,and ammonia is evolved.Continue the heating until the liquid becomes turbid,then cool.Dissolve the fused mass in a mixture of 10mLof water and 1mLof sodium hydroxide solution (1in 10),and add 1drop of cupric sulfate TS:the solution acquires a reddish-violet color.
Dissolve 100mg in 1mLof water,and add 1mLof nitric acid:a white crystalline precipitate of urea nitrate is formed.
Melting range á741ñ:
between 132and 135.
Residue on ignition á281ñ:
not more than 0.1%.
Dissolve 5.0g in 50mLof warm alcohol,and if any insoluble residue remains,filter the solution on a tared filter,wash the residue and the filter with 20mLof warm alcohol,and dry at 105for 1hour:the weight of the residue does not exceed 2mg (0.04%).
A2.0-g portion shows no more chloride than corresponds to 0.20mLof 0.020Nhydrochloric acid (0.007%).
A2.0-g portion shows no more sulfate than corresponds to 0.20mLof 0.020Nsulfuric acid (0.010%).
Heavy metals á231ñ
Dissolve 1.0g in 20mLof water,and add 5mLof 0.1Nhydrochloric acid:the limit is 0.002%.
Where the label states that Urea is sterile,it meets the requirements for Sterility Tests á71ñand for Bacterial endotoxinsunder Urea for Injection.Where the label states that Urea must be subjected to further processing during the preparation of injectable dosage forms,it meets the requirements for Bacterial endotoxinsunder Urea for Injection.
Transfer about 500mg of Urea,accurately weighed,to a 200-mLvolumetric flask,dissolve in and dilute with water to volume,and mix.Pipet 2mLof this solution into a micro-Kjeldahl digestion flask,and proceed as directed under Nitrogen Determination,Method IIá461ñ,beginning with Add 1g of a powdered mixture.[NOTEIn this procedure,continue heating the flask until fuming begins,then heat for 1additional hour.]Each mLof 0.01Nacid is equivalent to 0.3003mg of CH4N2O.
Staff Liaison:Andrzej Wilk,Ph.D.,Senior Scientific Associate
Expert Committee:(PA5)Pharmaceutical Analysis 5
Pharmacopeial Forum:Volume No.29(5)Page 1589
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