Identification—
Dissolve a portion of finely powdered Tablets in methanol to obtain a test solution containing about 2.5mg of molindone hydrochloride per mL.Separately apply 5µLof the test solution and 5µLof a Standard solution of
USP Molindone Hydrochloride RSin methanol containing 2.5mg per mLto a thin-layer chromatographic plate (see
Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel mixture.Allow the spots to dry,protect the chromatogram from light,and develop in a solvent system consisting of a mixture of alcohol and 1Nhydrochloric acid (95:5).Remove the plate from the developing chamber,mark the solvent front,and allow the solvent to evaporate.Locate the spots on the plate by spraying with Dragendorff's reagent,prepared as directed for
Visualization Technique 3under
Ordinary Impurities á466ñ:the
RFvalue of the principal spot obtained from the test solution corresponds to that obtained from the Standard solution.
Dissolution á711ñ—
Medium:
0.1Nhydrochloric acid;900mL.
Apparatus 1:
100rpm.
Time:
30minutes.
Solvent A—
Mix 300mLof methanol and 700mLof 0.1Nhydrochloric acid.
Solvent B—
Mix 75mLof methanol and 25mLof 0.1Nhydrochloric acid.
Standard solution—
Transfer about 100mg of
USP Molindone Hydrochloride RS,accurately weighed,to a 250-mLvolumetric flask,and dissolve in and dilute with
Solvent Ato volume.Pipet 5.0mLof this stock solution into a 250-mLvolumetric flask,and dilute with
Solvent Ato volume.Pipet 15.0mLof the diluted stock solution into a 50-mLvolumetric flask,and dilute with
Solvent Ato volume.
Test solution—
Withdraw a portion of the solution under test,and filter,discarding the first 3mLof filtrate.Pipet 15.0mLof this solution into a 25-mLvolumetric flask,and dilute with Solvent Bto volume.
Mobile phase—
Dissolve 1.08g of sodium 1-octanesulfonate in 480mLof water.Add 520mLof methanol,2.0mLof acetic acid,and 0.4mLof triethylamine,and mix.Make adjustments if necessary (see
System Suitabilityunder
Chromatography á621ñ).
Chromatographic system (see Chromatography á621ñ)—
The liquid chromatograph is equipped with a 254-nm UVdetector and a 4.6-mm ×25-cm column that contains packing L11.The flow rate is about 1.5mLper minute.
Procedure—
Separately inject equal volumes (about 100µL)of the Standard solutionand the Test solutioninto the chromatograph,record the chromatograms,and measure the peak heights.Determine the amount of molindone hydrochloride (C16H24N2O2·HCl)dissolved.
Tolerances—
Not less than 80%(Q)of the labeled amount of C16H24N2O2·HCl is dissolved in 30minutes.
Assay—
Mobile phase
,
Solvent mixture,
Internal standard solution,
Standard preparation,and
Chromatographic system—Proceed as directed in the
Assayunder
Molindone Hydrochloride.
Assay preparation—
Accurately weigh not less than 20Tablets,grind the Tablets to a homogeneous mixture,and transfer an accurately weighed portion,equivalent to about 50mg of molindone hydrochloride,to a 250-mLconical flask.Add 10.0mLof Internal standard solutionand 90.0mLof Solvent mixture,shake for 30minutes,and filter.
Procedure—
Proceed as directed for
Procedurein the
Assayunder
Molindone Hydrochloride.Calculate the quantity,in mg,of molindone hydrochloride (C
16H
24N
2O
2·HCl)in the portion of Tablets taken by the formula:
100C(RU/RS),
in which
Cis the concentration,in mg per mL,of
USP Molindone Hydrochloride RSin the
Standard preparation,and
RUand
RSare the ratios of the peak response of molindone to that of butylparaben obtained from the
Assay preparationand the
Standard preparation,respectively.