Packaging and storage—
Preserve in tight,light-resistant containers,and store at controlled room temperature.
Labeling—
Label it to indicate that it is for veterinary use only.
Identification—
Shake a quantity equivalent to about 1g with 5mLof diluted hydrochloric acid and 10mLof water.Filter,and to the filtrate add 2.5Nsodium hydroxide dropwise until a precipitate forms and redissolves.Add diluted hydrochloric acid dropwise until a precipitate forms.Collect the precipitate on a very fine filter,and wash it with water and with ether:the sulfadimethoxine so obtained meets the requirements for the Identificationtests under Sulfadimethoxine.
pHá791ñ:
between 7.0and 8.0,in a solution (1in 20).
Assay—
Mobile phase,Standard preparation,and Chromatographic system—
Proceed as directed in the
Assayunder
Sulfadimethoxine.
Assay preparation—
Transfer an accurately weighed portion of Powder,equivalent to about 50mg of sulfadimethoxine,to a 250-mLvolumetric flask,add about 200mLof Mobile phase,and swirl to dissolve.Dilute with Mobile phaseto volume,and mix.Protect this solution from light.
Procedure—
Proceed as directed in the
Assayunder
Sulfadimethoxine.Calculate the quantity,in mg,of sulfadimethoxine (C
12H
14N
4O
4S)in the portion of Powder taken by the formula:
250C(rU/rS),
in which
Cis the concentration,in mg per mL,of
USP Sulfadimethoxine RSin the
Standard preparation;and
rUand
rSare the peak responses obtained from the
Assay preparationand the
Standard preparation,respectively.