Benzeneacetic acid,
-hydroxy-, (±)-, compd. with 1,3,5,7-tetraazatricyclo[3.3.1.1
3,7]decane (1:1).
Hexamethylenetetramine mono-(±)-mandelate
[
587-23-5].
Packaging and storage—
Preserve in well-closed containers.
Loss on drying 
731
—
Dry it over silica gel for 18 hours: it loses not more than 1.5% of its weight.
Chloride 221—
Dissolve 1.0 g in 10 mL of water, and add gradually 500 mg of anhydrous sodium carbonate. Evaporate to dryness, and ignite the residue at a dull-red heat. Add 20 mL of 2 N nitric acid, stir gently, and filter: the filtrate shows no more chloride than corresponds to 0.15 mL of 0.020 N hydrochloric acid (0.01%).
Sulfate—
Dissolve 0.20 g in 10 mL of water, and add 5 drops of 3 N hydrochloric acid and 5 drops of
barium chloride TS: no turbidity appears within 1 minute.
Heavy metals 231—
Dissolve 1.3 g in 10 mL of water, add 2 mL of 3 N hydrochloric acid, and dilute with water to 25 mL: the limit is 0.0015%.
Organic volatile impurities, Method I 467:
meets the requirements.
Mandelic acid content—
Transfer about 90 mg, accurately weighed, to a 250-mL conical flask containing 50 mL of water. When solution is complete, titrate the magnetically stirred solution with 0.05 N ceric ammonium nitrate VS, determining the endpoint potentiometrically. Each mL of 0.05 N ceric ammonium nitrate is equivalent to 3.804 mg of C8H8O3.
Assay—
0.05 N Silver nitrate in dehydrated alcohol—
Dissolve, by stirring, about 8.5 g of silver nitrate in 1000 mL of dehydrated alcohol. Transfer about 100 mg, accurately weighed, of sodium chloride, previously dried at 110
for 2 hours, to a 100-mL beaker, and dissolve in 50 mL of 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 60 mg of Methenamine Mandelate, accurately weighed, to a 250-mL conical flask. Add 15 mL of dehydrated alcohol, stir to dissolve, and add 40 mL of chloroform. Titrate with 0.05 N 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 mL of 0.05 N silver nitrate is equivalent to 7.308 mg of C6H12N4·C8H8O3.
;)