A: Infrared Absorption á197Mñ:undried.

B: Ultraviolet Absorption á197Uñ—

Matching solutions— Prepare three solutions,A,B,and C,containing,respectively,the following parts of cobaltous chloride CS,ferric chloride CS,cupric sulfate CS,and dilute hydrochloric acid (1in 40):

A— 3.0:3.0:2.4:31.6

B— 1.0:2.4:0.4:36.2

C— 0.6:2.4:0:37.0

Procedure— Prepare a test solution by dissolving 100mg of Bromocriptine Mesylate in 10.0mLof methanol,and compare this solution with 10-mLportions of the Matching solutionsin suitable matched tubes:the solution is clear and not darker in color than Matching solutions A,B,and C.

Test solution: 10mg per mL,in a mixture of methylene chloride and methanol (1:1).

Citrate buffer— Prepare a 0.1Ncitric acid solution,adjust with hydrochloric acid to a pHof 2.0,and mix.

Diluting solution— Prepare a mixture of methanol and Citrate buffer(1:1).

Solution A— Mix 57mLof 0.01Mphosphate buffer having a pHof 7.0and 43mLof acetonitrile.

Solution B— Mix 40mLof 0.01Mphosphate buffer having a pHof 7.0and 60mLof acetonitrile.

Mobile phase— Use variable mixtures of Solution Aand Solution Bas directed for Chromatographic system.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

System suitability solution— Dissolve accurately weighed quantities of a-ergocryptine and Bromocriptine Mesylate in Diluting solutionto obtain a solution containing about 2.0mg of each per mL.

Standard solution— Dissolve an accurately weighed quantity of USP Bromocriptine Mesylate RSin methanol,dilute quantitatively with an equal volume of Citrate buffer,and dilute quantitatively,and stepwise if necessary,with Diluting solutionto obtain a solution having a known concentration of about 4.6µg per mL.

Test solution— Transfer about 46mg of Bromocriptine Mesylate,accurately weighed,to a 10-mLvolumetric flask,dissolve in 5.0mLof methanol,dilute with Citrate bufferto volume,and mix.

Chromatographic system (see Chromatography á621ñ)— The liquid chromatograph is equipped with a 300-nm detector and a 4.6-mm ×15-cm column that contains 3-µm packing L1.The flow rate is about 2mLper minute.The chromatograph is programmed as follows. Chromatograph the System suitability solution,and record the peak responses as directed for Procedure:the relative retention times are about 0.46for a-ergocryptine and 1.0for bromocriptine mesylate;the resolution,R,between a-ergocryptine and bromocriptine mesylate is not less than 15;and the tailing factor is not more than 1.5.Chromatograph the Standard solution,and record the peak responses as directed for Procedure:the retention time for the bromocriptine mesylate peak is between 17and 20minutes;and the relative standard deviation for replicate injections is not more than 10.0%.

Procedure— Separately inject equal volumes (about 20µL)of the Standard solutionand the Test solutioninto the chromatograph,record the chromatograms,and measure all of the peak responses.Calculate the percentage of each impurity in the portion of Bromocriptine Mesylate taken by the formula: in which F,the relative response factor,is equal to 0.7for any peaks eluting at a relative retention time of about 0.9or less,and is equal to 1.0for all other peaks;Cis the concentration,in mg per mL,of USP Bromocriptine Mesylate RSin the Standard solution;Wis the weight,in mg,of Bromocriptine Mesylate taken for the Test solution;riis the peak response for each impurity obtained from the Test solution;and rSis the peak response for bromocriptine obtained from the Standard solution:not more than 0.1%of any individual impurity is found;and not more than 0.5%of total impurities is found.

Solvent— Use dimethyl sulfoxide.