A: Infrared Absorption 197K.

B: The RF values of the principal fluorescent spot and the principal blue spot obtained from the Test preparation correspond to those obtained from Standard preparation A in the chromatogram prepared as directed in the test for Related alkaloids.

Test solution: 5 mg per mL, in water.

(Official January 1, 2007)

Mobile phase— Prepare a filtered and degassed mixture of 0.015 M monobasic potassium phosphate and acetonitrile (4:1). Make adjustments if necessary (see System Suitability under Chromatography 621).

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

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

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

Chromatographic system (see Chromatography 621)—The liquid chromatograph is equipped with a fluorometric detector set at an excitation wavelength of 315 nm, and an emission wavelength that is set to zero, using a cutoff filter that passes light from about 418 to 700 nm, and a 4.6-mm × 25-cm column that contains packing L7 maintained at 30. The flow rate is about 2 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed under Procedure: the column efficiency is not less than 1000 theoretical 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 20 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of C20H25N3O2·C4H4O4 in the Methylergonovine Maleate taken by the formula: in which C is the concentration, in µg per mL, of USP Methylergonovine Maleate RS in the Standard preparation, and rU and rS are the fluorescence intensity responses obtained from the Assay preparation and the Standard preparation, respectively.