Related alkaloids
[NOTEConduct this test promptly, without exposure to daylight and with minimum exposure to artificial light.
]
Adsorbent:
0.25-mm layer of chromatographic silica gel mixture.
Solvent mixture
Prepare a mixture of alcohol and ammonium hydroxide (9:1).
Standard preparation
Prepare a solution of
USP Ergonovine Maleate RS in
Solvent mixture having a known concentration of about 10 mg per mL.
Standard dilutions
Prepare a series of dilutions of the Standard preparation in Solvent mixture having known concentrations of about 0.20, 0.10, and 0.05 mg per mL. Use immediately after preparation.
Test preparation
Immediately prior to use, prepare a solution of Ergonovine Maleate in Solvent mixture having a concentration of about 10 mg per mL.
Application volume:
5 µL.
Developing solvent system:
a mixture of chloroform, methanol, and water (75:25:3), equilibrated for 30 minutes.
Procedure
Apply 5-µL portions of the
Standard preparation, each of the three
Standard dilutions, and the
Test preparation, and proceed as directed for
Thin-Layer Chromatography under
Chromatography 621. Locate the spots on the plate by spraying thoroughly and evenly with a solution prepared by dissolving 1 g of
p-dimethylaminobenzaldehyde in a cooled mixture of 50 mL of alcohol and 50 mL of hydrochloric acid. Immediately dry in a stream of nitrogen for about 2 minutes: the
RF value of the principal spot obtained from the
Test preparation corresponds to that obtained from the
Standard preparation. Estimate the concentration of any other spots observed in the chromatogram of the
Test preparation by comparison with the
Standard dilutions. The spots from the 0.20, 0.10, and 0.05 mg per mL dilutions are equivalent to 2.0%, 1.0%, and 0.50% of impurities, respectively. The sum of the impurities is not greater than 2.0%.
Assay
Standard preparation
Using a suitable quantity of
USP Ergonovine Maleate RS, accurately weighed, prepare a solution in water having a known concentration of about 40 µg per mL.
Assay preparation
Transfer about 40 mg of Ergonovine Maleate, accurately weighed, to a 100-mL volumetric flask, dilute with water to volume, and mix. Dilute 10.0 mL of this solution with water to 100.0 mL.
Procedure
Transfer 5.0 mL each of the
Standard preparation, the
Assay preparation, and water to provide a blank, to separate conical flasks. Add 10.0 mL of
p-dimethylaminobenzaldehyde TS with constant swirling to each, and allow to stand for 20 minutes. Concomitantly determine the absorbances of the solutions in 1-cm cells at the wavelength of maximum absorbance at about 555 nm, with a suitable spectrophotometer, against the blank. Calculate the quantity, in mg, of C
19H
23N
3O
2·C
4H
4O
4 taken by the formula:
C(AU / AS),
in which
C is the concentration, in µg per mL, of
USP Ergonovine Maleate RS in the
Standard preparation, and
AU and
AS are the absorbances of the solutions from the
Assay preparation and the
Standard preparation, respectively.