Packaging and storage—
Preserve in well-closed, light-resistant containers.
Labeling—
The label indicates whether it contains tartaric acid as a stabilizer.
Identification—
B:
The retention time of the major peak in the chromatogram of the
Assay preparation corresponds to that of the
Standard preparation as obtained in the
Assay.
C:
A solution (1 in 100) responds to the tests for
Chloride 
191
.
Secondary amines—
Dissolve 100 mg in 2 mL of methylene chloride in a centrifuge tube. Transfer to a second tube 2 mL of a Standard solution of diethylamine hydrochloride (dried at 105
for 2 hours before being used) in methylene chloride having a known concentration of 250 µg per mL. Treat each solution as follows. Extract with 2 mL of a buffer solution containing 5.7 g of sodium carbonate and 3.0 g of sodium bicarbonate per 100 mL of water. Centrifuge, if necessary, to clarify the upper phase, and immediately transfer 0.5 mL of it to a spot plate. Immediately add 2 drops of acetaldehyde TS, and then, in rapid succession, add 1 drop of sodium nitroferricyanide solution (1 in 100) to each spot. Immediately and simultaneously stir both spots to mix the reagents: any blue color produced within 3 minutes by the test solution is not more intense than that of the Standard solution (not more than 0.5% of secondary amines as diethylamine hydrochloride).
Free bromine—
One drop of a solution (1 in 10) produces no discoloration when placed upon starch iodide paper.
Limit of hydrobromic acid and bromide—
To 10 mL of a solution (1 in 10) add 1 mL of sodium hydroxide solution (1 in 10), extract with about 25 mL of chloroform, and discard the chloroform extract. Add 1 mL of 6 N hydrochloric acid, 0.5 mL of chloroform, and 0.5 mL of freshly prepared chloramine T solution (1 in 10), and shake vigorously: no yellow or brown-red color is produced in the chloroform layer.
Chromatographic purity—
Phosphate buffer—
Dissolve 136.1 g of monobasic potassium phosphate in 900 mL of water, add 3.2 mL of phosphoric acid, dilute with water to 1000 mL, and mix.
Diluent—
Prepare a mixture of water, Phosphate buffer, and acetonitrile (8:1:1).
Mobile phase—
Mix 100 mL of acetonitrile, 100 mL of
Phosphate buffer, 7.0 mL of diethylamine, and sufficient water to make 1 L. Filter, and degas before use. Make adjustments if necessary (see
System Suitability under
Chromatography 621).
Test preparation—
Transfer 100 mg of Diethylpropion Hydrochloride, accurately weighed, to a 50-mL volumetric flask, dissolve in about 40 mL of Diluent, add Diluent to volume, and mix.
Standard preparation—
Dissolve an accurately weighed quantity of
USP Diethylpropion Hydrochloride RS in
Diluent, and dilute quantitatively, and stepwise if necessary, with
Diluent to obtain a solution having a known concentration of about 0.01 mg per mL.
System suitability solution—
Prepare a solution in
Diluent containing about 25 µg of 2-ethylaminopropiophenone hydrochloride and 50 µg of
USP Diethylpropion Hydrochloride RS per mL.
Chromatographic system
(see
Chromatography 621)—The liquid chromatograph is equipped with a 254-nm detector and a 4.6-mm × 15-cm column that contains packing L11. The flow rate is about 1 mL per minute. Chromatograph the
System suitability solution, and record the peak responses as directed for
Procedure: the relative retention times are about 0.5 for 2-ethylaminopropiophenone and 1.0 for diethylpropion, and the resolution,
R, between the 2-ethylaminopropiophenone and diethylpropion peaks is not less than 6.0. Chromatograph the
Standard preparation, and record the peak responses as directed for
Procedure: the relative standard deviation for replicate injections is not more than 1.0%.
Procedure—
Separately inject equal volumes (about 20 µL) of the Standard preparation and the Test preparation into the chromatograph, record the chromatograms, and measure the peak responses. The sum of all of the peak responses, excluding the solvent peak responses and the diethylpropion response, from the Test preparation is not greater than the diethylpropion response from the Standard preparation (0.5%).
Organic volatile impurities, Method I 467:
meets the requirements.
Assay—
Phosphate buffer—
Dissolve 136.1 g of monobasic potassium phosphate in 900 mL of water, add 4.3 mL of phosphoric acid, dilute with water to 1000 mL, and mix.
Mobile phase—
Prepare a suitable mixture of water, acetonitrile,
Phosphate buffer, and 1.0
M sodium nitrate (730:200: 50:20), filter through a membrane filter (0.7-µm or finer porosity), and degas. Make adjustments if necessary (see
System Suitability under
Chromatography 621).
Standard preparation—
Dissolve an accurately weighed quantity of
USP Diethylpropion Hydrochloride RS in
Mobile phase, and dilute quantitatively, and stepwise if necessary, with
Mobile phase to obtain a solution having a known concentration of about 40 µg per mL.
Assay preparation—
Transfer about 100 mg of Diethylpropion Hydrochloride, accurately weighed, to a 250-mL volumetric flask, dissolve in Mobile phase, dilute with Mobile phase to volume, and mix. Transfer 10.0 mL of this solution to a 100-mL volumetric flask, dilute with Mobile phase to volume, and mix.
Chromatographic system
(see
Chromatography 621)—The liquid chromatograph is equipped with a 254-nm detector and a 4-mm × 30-cm column that contains packing L1. The flow rate is about 1.5 mL per minute. Chromatograph the
System suitability preparation, and record the peak responses as directed for
Procedure: the relative retention times are about 0.5 for diethylpropion hydrochloride and 1.0 for benzoic acid, and the resolution,
R, between the diethylpropion hydrochloride and benzoic acid peaks is not less than 2.0. Chromatograph the
Standard preparation, and record the peak responses as directed for
Procedure: the relative standard deviation for replicate injections is not more than 1.0%.
Procedure—
Separately inject equal volumes (about 50 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 C
13H
19NO·HCl in the portion of Diethylpropion Hydrochloride taken by the formula:
2.5C(rU / rS),
in which
C is the concentration, in µg per mL, of
USP Diethylpropion Hydrochloride RS in the
Standard preparation, and
rU and
rS are the peak responses obtained from the
Assay preparation and the
Standard preparation, respectively.
;)
