Solvent mixture, Standard preparation, and Standard dilutions— Prepare as directed in the test for Related alkaloids under Ergonovine Maleate.

Test preparation— Immediately prior to use, transfer a volume of Injection, equivalent to about 5 mg of ergonovine maleate, to a separator, and extract with three 5-mL portions of chloroform. Discard the chloroform extracts. Render alkaline to litmus with 6 N ammonium hydroxide, and extract with three 5-mL portions of chloroform. Evaporate the combined extracts with the aid of a stream of nitrogen, but without heat, to dryness. Dissolve the residue so obtained in 0.5 mL of Solvent mixture.

Procedure— Proceed as directed for Procedure in the test for Related alkaloids under Ergonovine Maleate.

0.05 M Phosphate buffer— Dissolve 6.8 g of monobasic potassium phosphate in 600 mL of water and adjust with phosphoric acid to a pH of 2.1. Dilute with water to 1000 mL, and mix.

Mobile phase— Prepare a suitable and degassed solution of 0.05 M Phosphate buffer and acetonitrile (80:20) such that the retention time is approximately 3 minutes with a flow rate of 1 mL per minute.

Standard preparation— Dissolve an accurately weighed quantity of USP Ergonovine Maleate RS in Mobile phase, adding sufficient water to equal 10% of the final volume, to obtain a solution having a known concentration of about 0.02 mg per mL.

Assay preparation— Quantitatively dilute an accurately measured volume of the Injection, equivalent to about 2 mg of ergonovine maleate, with Mobile phase and water, if necessary, to obtain a solution having a concentration of about 0.02 mg per mL in which the Injection volume plus any added water constitutes 10% of the final volume.

Chromatographic system (see Chromatography 621)—The liquid chromatograph is equipped with a 312-nm detector and a 3-mm × 30-cm column that contains packing L1. Chromatograph five replicate injections of the Standard preparation, and record the peak responses as directed under Procedure: the relative standard deviation is not more than 3.0%.

Procedure— By means of a suitable sampling valve, introduce equal volumes (about 100 µL) of the Assay preparation and the Standard preparation into the chromatograph. Measure the peak responses of Ergonovine Maleate, at corresponding retention times, obtained from the Assay preparation and the Standard preparation. Calculate the quantity, in mg, of C19H23N3O2·C4H4O4 in each mL of the Injection taken by the formula: in which C is the concentration, in mg per mL, of USP Ergonovine Maleate RS in the Standard preparation, V is the volume, in mL, of Injection taken, D is the dilution factor, and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.