A: It meets the requirements under Identification—Organic Nitrogenous Bases á181ñ.

B: It meets the requirements of the test for Citrate á191ñ.

Test solution: methanol.

Standard solution: methanol.

Eluant: a mixture of methanol and ammonium hydroxide (100:1.5).

Visualization: 16.

Phosphate buffer,Mobile phase,andChromatographic system— Proceed as directed in the Assay.

Standard solution— Prepare a solution of USP Diethylcarbamazine Citrate RSin Phosphate bufferhaving a known concentration of about 0.003mg per mL.

Test solution— Transfer about 300mg of Diethylcarbamazine Citrate,accurately weighed,to a 100-mLvolumetric flask,add 100mLof Phosphate buffer,and mix.Filter or centrifuge,and use the clear filtrate or supernatant.

Procedure— Separately inject equal volumes (about 20µL)of the Standard solutionand the Test solutioninto the chromatograph,record the chromatograms,and measure the responses for all the peaks.Calculate the percentage of each impurity in the portion of Diethylcarbamazine Citrate taken by the formula: in which Cis the concentration,in mg per mL,of USP Diethylcarbamazine Citrate RSin the Standard solution;Wis the weight,in mg,of Diethylcarbamazine Citrate taken to prepare the Test solution;riis the peak response for each impurity obtained from the Test solution;and rSis the peak response for diethylcarbamazine citrate obtained from the Standard solution.Not more than 0.1%of any individual impurity is found.

Phosphate buffer— Dissolve 31.24g of monobasic potassium phosphate in 1000mLof water.

Mobile phase— Dissolve 10g of monobasic potassium phosphate in 1000mLof water.Prepare a filtered and degassed mixture of 900mLof this solution and 100mLof methanol.

Standard preparation— Transfer about 5mg of USP Diethylcarbamazine Citrate RS,accurately weighed,to a 50-mLvolumetric flask,dissolve in and dilute with Phosphate bufferto volume,and mix.

Assay preparation— Transfer about 5mg of Diethylcarbamazine Citrate,accurately weighed,to a 50-mLvolumetric flask,dissolve in and dilute with Phosphate bufferto volume,and mix.

Chromatographic system— The liquid chromatograph is equipped with a 220-nm detector and a 3.9-mm ×15-cm column that contains 5-µm packing L1.The flow rate is about 0.8mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 20µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of C10H21N3O·C6H8O7in the portion of Diethylcarbamazine Citrate taken by the formula: in which Cis the concentration,in mg per mL,of USP Diethylcarbamazine Citrate RSin the Standard preparation;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.