Pyrimethamine
;)
2,4-Pyrimidinediamine,5-(4-chlorophenyl)-6-ethyl-.
2,4-Diamino-5-(p-chlorophenyl)-6-ethylpyrimidine [58-14-0].
»Pyrimethamine contains not less than 99.0percent and not more than 101.0percent of C12H13ClN4,calculated on the dried basis.
Packaging and storage—
Preserve in tight,light-resistant containers.
Identification—
A:
Infrared Absorption á197Kñ.
B:
Mix about 100mg with 500mg of anhydrous sodium carbonate,and ignite the mixture.Cool,add 5mLof hot water,heat for 5minutes on a steam bath,filter,and neutralize the filtrate with nitric acid:the solution responds to the test for Chloride á191ñ.
Loss on drying á731ñ—
Dry it at 105
for 4hours:it loses not more than 0.5%of its weight.
for 4hours:it loses not more than 0.5%of its weight.
Residue on ignition á281ñ:
not more than 0.1%.
Ordinary impurities á466ñ—
Test solution:
a mixture of methanol and chloroform (1:1).
Standard solution:
a mixture of methanol and chloroform (1:1).
Eluant:
a mixture of n-propyl alcohol,glacial acetic acid,and water (8:1:1).
Visualization:
2.
Organic volatile impurities,Method Vá467ñ:
meets the requirements.
Solvent—
Use dimethyl sulfoxide.
Assay—
Dissolve about 200mg of Pyrimethamine,accurately weighed,in 25mLof glacial acetic acid,warming slightly to effect solution.Cool the solution to room temperature,add 4drops of quinaldine red TS,and titrate with 0.1Nperchloric acid VS.Perform a blank determination,and make any necessary correction.Each mLof 0.1Nperchloric acid is equivalent to 24.87mg of C12H13ClN4.
Auxiliary Information—
Staff Liaison:Behnam Davani,Ph.D.,MBA,Senior Scientist
Expert Committee:(PA7)Pharmaceutical Analysis 7
USP28–NF23Page 1686
Phone Number:1-301-816-8394