A:Infrared Absorption á197Kñ.

B:Ultraviolet Absorption á197Uñ—

Solution A— Dissolve 6.8g of monobasic potassium phosphate in 1000mLof water,add 2mLof triethylamine,and adjust with phosphoric acid to a pHof 2.5.Filter and degas.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Solution B— Prepare a mixture of Solution Aand acetonitrile (85:15).

Mobile phase— Use variable mixtures of Solution Aand Solution Bas directed for Chromatographic system.

Diluting solution— Dissolve 0.25g of sodium metabisulfite in 1000mLof Mobile phase A.

Standard stock solution— Dissolve an accurately weighed quantity of USP Inamrinone RSin Diluting solutionto obtain a solution having a known concentration of about 2mg per mL.

Standard solution— Dilute a suitable volume of Standard stock solutionquantitatively,and stepwise if necessary,with Diluting solutionto obtain a solution having a known concentration of 4µg of USP Inamrinone RSper mL.

System suitability solution— Prepare a solution of USP Inamrinone Related Compound A RSin Diluting solutionhaving a concentration of 2mg per mL.Transfer 5.0mLof this solution and 5.0mLof the Standard stock solutionto a 50-mLvolumetric flask,dilute with Diluting solutionto volume,and mix.

Test solution— Transfer about 100mg of Inamrinone,accurately weighed,to a 50-mLvolumetric flask,dissolve in and dilute with Diluting solutionto volume,and mix.[NOTE—Use this solution within 1hour after preparation.]

Chromatographic system(see Chromatography á621ñ)— The liquid chromatograph is equipped with a 315-nm detector and a 4.0-mm ×25-cm analytical column that contains packing L1and is fitted with a guard column that contains packing L1.The flow rate is about 1.0mLper minute.The chromatograph is programmed as follows.

Procedure— Separately inject equal volumes (about 15µL)of the Standard solutionand the Test solutioninto the chromatograph,record the chromatograms allowing the Test solutionto elute for not less than five times the retention times of inamrinone,and measure the areas of all the peaks observed in the chromatogram of the Test solution.Calculate the percentage of each impurity in the portion of Inamrinone taken by the formula: in which Cis the concentration,in mg per mL,of USP Inamrinone RSin the Standard solution;Wis the weight,in mg,of inamrinone taken for the Test solution;riis the response of each impurity peak;and rSis the mean response for the Standard solution:not more than 0.2%of any individual impurity is found;and the sum of all impurities is not more than 1.0%.