A: Infrared Absorption 197M: undried.

B: Ultraviolet Absorption 197U—

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 (1 in 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 100 mg of Bromocriptine Mesylate in 10.0 mL of methanol, and compare this solution with 10-mL portions of the Matching solutions in suitable matched tubes: the solution is clear and not darker in color than Matching solutions A, B, and C.

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

Citrate buffer— Prepare a 0.1 N citric acid solution, adjust with hydrochloric acid to a pH of 2.0, and mix.

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

Solution A— Mix 57 mL of 0.01 M phosphate buffer having a pH of 7.0 and 43 mL of acetonitrile.

Solution B— Mix 40 mL of 0.01 M phosphate buffer having a pH of 7.0 and 60 mL of acetonitrile.

Mobile phase— Use variable mixtures of Solution A and Solution B as directed for Chromatographic system. Make adjustments if necessary (see System Suitability under Chromatography 621).

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

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

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

Chromatographic system (see Chromatography 621)— 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 2 mL per 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 0.46 for -ergocryptine and 1.0 for bromocriptine mesylate; the resolution, R, between -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 17 and 20 minutes; and the relative standard deviation for replicate injections is not more than 10.0%.

Procedure— Separately inject equal volumes (about 20 µL) of the Standard solution and the Test solution into 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 0.7 for any peaks eluting at a relative retention time of about 0.9 or less, and is equal to 1.0 for all other peaks; C is the concentration, in mg per mL, of USP Bromocriptine Mesylate RS in the Standard solution; W is the weight, in mg, of Bromocriptine Mesylate taken for the Test solution; ri is the peak response for each impurity obtained from the Test solution; and rS is the peak response for bromocriptine obtained from the Standard solution: not more than 0.4% of bromcriptinin is found; not more than 0.1% of any individual impurity is found; and not more than 1.0% of total impurities is found.