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

Apparatus 2: 100rpm.

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 Methysergide Maleate RSin the same medium having a known concentration of about 2.2µg 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 C21H27N3O2·C4H4O4is dissolved in 30minutes.

Mobile phase— Dissolve 6.8g of monobasic potassium phosphate in 700mLof water,add 300mLof acetonitrile,and mix.Filter through a 0.45-µm membrane,and degas under vacuum.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Solvent mixture— Dissolve 10g of tartaric acid in 1liter of water,add 1liter of methanol,and mix.

Standard preparation— Dissolve an accurately weighed quantity of USP Methysergide Maleate RSin Solvent mixturewith the help of sonication,and dilute quantitatively,and stepwise if necessary,with the same solvent to obtain a solution having a known concentration of about 0.1mg per mL.

Assay preparation— Weigh and finely powder not less than 20Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 10mg of methysergide maleate,to a 100-mLvolumetric flask.Add 75mLof Solvent mixture,and shake by mechanical means for 60minutes.Add Solvent mixtureto volume,mix,and filter through a 0.45-µm membrane,discarding the first 20mLof the filtrate.

Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 318-nm detector and a 4.6-mm ×15-cm column that contains packing L7.The flow rate is about 2mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the column efficiency determined from the analyte peak is not less than 1000theoretical plates,the tailing factor for the analyte peak is not more than 2.5,the resolution,R,between the analyte and the closest adjacent peak is not less than 1.0,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 methysergide maleate (C21H37N3O2·C4H4O4)in the portion of Tablets taken by the formula: in which Cis the concentration,in mg per mL,of USP Methysergide Maleate RSin the Standard preparation;,and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.