Packaging and storage— Preserve in well-closed containers.

USP Reference standards á11ñ— USP Chloroquine Phosphate RS.

Identification— Afiltered solution of the Tablets responds to Identificationtests Aand Bunder Chloroquine Hydrochloride Injection.

Dissolution á711ñ—

Uniformity of dosage units á905ñ: meet the requirements.

Assay— Weigh and finely powder not less than 20Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 800mg of chloroquine phosphate,to a 200-mLvolumetric flask,add about 100mLof water,and shake by mechanical means for about 20minutes.Add water to volume,mix,and filter,discarding the first 50mLof the filtrate.Pipet 50mLof the clear filtrate into a 250-mLseparator,add 5mLof 6Nammonium hydroxide,agitate,and extract the liberated chloroquine with five 25-mLportions of chloroform.Wash the combined chloroform extracts with 10mLof water,and extract the water washing with 10mLof chloroform.Evaporate the combined chloroform extracts on a steam bath to about 10mL,then add 50mLof dilute hydrochloric acid (1in 250),and continue heating on the steam bath until the odor of chloroform is no longer perceptible.Transfer the solution to a 200-mLvolumetric flask,wash the evaporating vessel with portions of dilute hydrochloric acid (1in 1000),adding the washings to the volumetric flask,add more of the same dilute hydrochloric acid to volume,and mix.Dilute this solution quantitatively and stepwise with dilute hydrochloric acid (1in 1000)to obtain an estimated concentration of 10µg per mL.Dissolve an accurately weighed quantity of USP Chloroquine Phosphate RSin dilute hydrochloric acid (1in 1000),and dilute quantitatively and stepwise with the same dilute hydrochloric acid to obtain a Standard solution having a known concentration of about 10µg per mL.Concomitantly determine the absorbances of both solutions in 1-cm cells at the wavelength of maximum absorbance at about 343nm,with a suitable spectrophotometer,using dilute hydrochloric acid (1in 1000)as the blank.Calculate the quantity,in mg,of C18H26ClN3·2H3PO4in the portion of Tablets taken by the formula: in which Cis the concentration,in µg per mL,of USP Chloroquine Phosphate RSin the Standard solution,and AUand ASare the absorbances of the solution from Tablets and the Standard solution,respectively.

Expert Committee:(PA7)Pharmaceutical Analysis 7

USP28–NF23Page 445

Phone Number:1-301-816-8394