A: Infrared Absorption á197Kñ.

B: The RFvalues of the principal fluorescent spot and the principal blue spot obtained from the Test preparationcorrespond to those obtained from Standard preparation Ain the chromatogram prepared as directed in the test for Related alkaloids.

Test solution: 5mg per mL,in water.

Mobile phase— Prepare a filtered and degassed mixture of 0.015Mmonobasic potassium phosphate and acetonitrile (4:1).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Solvent mixture— Transfer 2.5g of tartaric acid to a 1000-mLvolumetric flask,add 500mLof water,and mix with shaking.Dilute with methanol to volume,and allow the mixture to cool before use.

Standard preparation— Transfer about 20mg of USP Methylergonovine Maleate RS,accurately weighed,to a 200-mLvolumetric flask.Add 150mLof Solvent mixture,and shake by mechanical means for 15minutes.Dilute with Solvent mixtureto volume,and mix.Quantitatively dilute a portion of this solution with Solvent mixtureto obtain a solution having a known concentration of about 4µg of USP Methylergonovine Maleate RSper mL.

Assay preparation— Transfer about 100mg of Methylergonovine Maleate,accurately weighed,to a 500-mLvolumetric flask.Add 300mLof Solvent mixture,and shake by mechanical means for 15minutes or until completely dissolved.Dilute with Solvent mixtureto volume,and mix.Quantitatively dilute a portion of this solution with Solvent mixtureto obtain the Assay preparationhaving a known concentration of about 4µg of Methylergonovine Maleate per mL.

Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a fluorometric detector set at an excitation wavelength of 315nm,and an emission wavelength that is set to zero,using a cutoff filter that passes light from about 418to 700nm,and a 4.6-mm ×25-cm column that contains packing L7maintained at 30.The flow rate is about 2mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed under Procedure:the column efficiency is not less than 1000theoretical plates,the tailing factor is not more than 2.0,and 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 C20H25N3O2·C4H4O4in the Methylergonovine Maleate taken by the formula: in which Cis the concentration,in µg per mL,of USP Methylergonovine Maleate RSin the Standard preparation,and rUand rSare the fluorescence intensity responses obtained from the Assay preparationand the Standard preparation,respectively.