A: The RFvalues of the principal fluorescent spot and the principal blue spot in the chromatogram of the Test preparationcorrespond to those in the chromatogram of the Standard preparation,as obtained in the test for Related alkaloidsunder Ergonovine Maleate,using the Tablets instead of Ergonovine Maleate.

B: Transfer a quantity of powdered Tablets,equivalent to about 4mg of methylergonovine maleate,to a separator,add 20mLof water,and render alkaline to litmus with sodium carbonate solution (1in 10).Extract with three 20-mLportions of chloroform,filter the combined chloroform extracts into a small evaporating dish,and evaporate on a steam bath to dryness.Dissolve the residue in a mixture of 6mLof water and 0.3mLof hydrochloric acid,and filter,if necessary:the solution so obtained exhibits a bluish fluorescence under UVlight.To this solution,add 2mLof a solution of glacial acetic acid in ethyl acetate (1in 2),and stratify 2mLof sulfuric acid,by pipetting,under the solution:a bluish purple ring appears at the interface of the two liquids.

Medium: tartaric acid solution (1in 200);900mL.

Apparatus 2: 75rpm.

Time: 30minutes.

Procedure— Filter a portion of the solution under test into a flask.Concomitantly determine the fluorescence intensity of this solution in comparison with a Standard solution of USP Methylergonovine Maleate RSin the same medium having a known concentration of about 0.22µg per mLin a fluorometer at an excitation wavelength of about 327nm and an emission wavelength of about 428nm,using tartaric acid solution (1in 200)as the blank.

Tolerances— Not less than 70%(Q)of the labeled amount of C20H25N3O2·C4H4O4is dissolved in 30minutes.

Solvent mixture— Mix 75volumes of chloroform,25volumes of methanol,and 1volume of ammonium hydroxide.

Detecting reagent— Cautiously dissolve 800mg of p-dimethylaminobenzaldehyde in a mixture of alcohol and sulfuric acid (101:11).

Test preparation— Transfer a quantity of finely powdered Tablets,equivalent to 5.0mg of methylergonovine maleate,to a suitable container,add 50mLof Solvent mixture,and stir with the aid of a magnetic stirrer for 40minutes.Filter,rinsing the container with two 10-mLportions of Solvent mixture.Evaporate the combined filtrates in vacuum at 25to 30,and dissolve the residue in 2.0mLof Solvent mixture.

Standard stock solution— Transfer 25mg of USP Methylergonovine Maleate RSto a 10-mLvolumetric flask,add Solvent mixtureto volume,and mix to obtain a solution having a known concentration of 2.5mg per mL.

Standard preparations A,B,C,andD— Dilute accurately measured volumes of Standard stock solutionquantitatively with Solvent mixture(designated below as parts by volume of Standard stock solutionin total parts by volume of the finished Standard preparation)to obtain Standard preparations,designated below by letter,having the following concentrations and percentage assignments:

A: (1in 20);125µg per mL(5.0%).

B: (1in 33);75µg per mL(3.0%).

C: (1in 100);25µg per mL(1.0%).

D: (1in 200);12.5µg per mL(0.5%).

Procedure— Apply separately 20µLof the Test preparationand 20µLof each Standard preparationto a suitable thin-layer chromatographic plate (see Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel mixture.Dry the plate with the aid of a stream of cool air.Position the plate in a chromatographic chamber,and develop the chromatograms in Solvent mixtureuntil the solvent front has moved about three-fourths of the length of the plate.Remove the plate from the developing chamber,mark the solvent front,and allow the solvent to evaporate in a stream of cool air.Examine the plate under long-wavelength UVlight.Mark the principal and any secondary fluorescent spots.Spray the plate with Detecting reagent,and mark the principal and secondary blue spots.Compare the intensities of any secondary spots observed in the chromatogram of the Test preparationwith those of the principal spots in the chromatograms of the Standard preparations:the sum of the intensities of secondary spots obtained from the Test preparationcorresponds to not more than 5.0%of related compounds.

Mobile phase,Solvent mixture,Standard preparation,andChromatographic system— Proceed as directed in the Assayunder Methylergonovine Maleate.

Assay preparation— Place 10Tablets in 1500-mLvolumetric flask,add 400mLof Solvent mixture,and shake by mechanical means for 15minutes or until completely disintegrated.Dilute with Solvent mixtureto volume,and mix.Allow the solution to settle for not less than 30minutes before use,and then filter to obtain the Assay preparation.

Procedure— Separately inject equal volumes (about 10µL)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 methylergonovine maleate (C20H25N3O2·C4H4O4)in the portion of Tablets taken by the formula: in which Lis the labeled quantity,in mg,of methylergonovine maleate in each Tablet,Dis the concentration,in µg per mL,of methylergonovine maleate in the Assay preparation,based on the labeled quantity per Tablet and the extent of dilution,Cis the concentration,in µg per mL,of USP Methylergonovine Maleate RSin the Standard preparation,and rUand rSare the responses obtained from the Assay preparationand the Standard preparation,respectively.