Methenamine Mandelate
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C6H12N4·C8H8O3 292.33

Benzeneacetic acid,a-hydroxy-,(±)-,compd.with 1,3,5,7-tetraazatricyclo[3.3.1.13,7]decane (1:1).

Hexamethylenetetramine mono-(±)-mandelate [587-23-5].
»Methenamine Mandelate contains not less than 95.5percent and not more than 102.0percent of C6H12N4·C8H8O3,and contains not less than 50.0percent and not more than 53.0percent of mandelic acid (C8H8O3),calculated on the dried basis.
Packaging and storage— Preserve in well-closed containers.
Identification,Infrared Absorption á197Kñ.
Loss on drying á731ñ— Dry it over silica gel for 18hours:it loses not more than 1.5%of its weight.
Residue on ignition á281ñ: not more than 0.1%.
Chloride á221ñ— Dissolve 1.0g in 10mLof water,and add gradually 500mg of anhydrous sodium carbonate.Evaporate to dryness,and ignite the residue at a dull-red heat.Add 20mLof 2Nnitric acid,stir gently,and filter:the filtrate shows no more chloride than corresponds to 0.15mLof 0.020Nhydrochloric acid (0.01%).
Sulfate— Dissolve 0.20g in 10mLof water,and add 5drops of 3Nhydrochloric acid and 5drops of barium chloride TS:no turbidity appears within 1minute.
Heavy metals á231ñ— Dissolve 1.3g in 10mLof water,add 2mLof 3Nhydrochloric acid,and dilute with water to 25mL:the limit is 0.0015%.
Organic volatile impurities,Method Iá467ñ: meets the requirements.
Mandelic acid content— Transfer about 90mg,accurately weighed,to a 250-mLconical flask containing 50mLof water.When solution is complete,titrate the magnetically stirred solution with 0.05Nceric ammonium nitrate VS,determining the endpoint potentiometrically.Each mLof 0.05Nceric ammonium nitrate is equivalent to 3.804mg of C8H8O3.
Assay—
0.05N Silver nitrate in dehydrated alcohol— Dissolve,by stirring,about 8.5g of silver nitrate in 1000mLof dehydrated alcohol.Transfer about 100mg,accurately weighed,of sodium chloride,previously dried at 110for 2hours,to a 100-mLbeaker,and dissolve in 50mLof water.Titrate with the silver nitrate solution to the potentiometric endpoint,using a silver billet indicator electrode and a silver-silver chloride double-junction reference electrode containing a potassium nitrate salt bridge.Calculate the normality of the titrant.
Procedure— Transfer about 60mg of Methenamine Mandelate,accurately weighed,to a 250-mLconical flask.Add 15mLof dehydrated alcohol,stir to dissolve,and add 40mLof chloroform.Titrate with 0.05N Silver nitrate in dehydrated alcohol,determining the endpoint potentiometrically,using a silver billet indicator electrode and a silver-silver chloride double-junction reference electrode containing a potassium nitrate salt bridge.Each mLof 0.05Nsilver nitrate is equivalent to 7.308mg of C6H12N4·C8H8O3.
Auxiliary Information— Staff Liaison:Behnam Davani,Ph.D.,MBA,Senior Scientist
Expert Committee:(PA7)Pharmaceutical Analysis 7
USP28–NF23Page 1243
Phone Number:1-301-816-8394