Identification
A:Infrared Absorption á197Kñ.
B:
The retention time of the major peak in the chromatogram of the Assay preparationcorresponds to that in the chromatogram of the Standard preparation,as obtained in the Assay.
Chromatographic purity
TEST1
Adsorbent:
a 0.25-mm layer of high-performance silica gel,previously washed with methanol.
Test solution
Prepare a solution of Bupropion Hydrochloride in methanol having a concentration of about 100.0mg per mL.
Standard solutions
Prepare a solution of m-chlorobenzoic acid in methanol containing about 0.5mg per mL.Dilute this solution quantitatively,and stepwise if necessary,with methanol to obtain solutions having known concentrations of about 0.3,0.2,and 0.1mg per mL.
Application volume:
2µL.
Developing solvent system:
a mixture of toluene,cyclohexane,and glacial acetic acid (47:47:6).
Procedure
Proceed as directed for
Thin-Layer Chromatographyunder
Chromatography á621ñ.Locate and quantitate the spots obtained by scanning the entire plate with a suitable densitometer at 254nm.Plot a standard curve of area versus concentrations of the
Standard solutions.From the standard curve,determine the percentages of
m-chlorobenzoic acid and any other impurity present:not more than 0.2%of
m-chlorobenzoic acid is found;and not more than 0.1%of any other individual impurity is found.
TEST2
Procedure
Using the chromatograms obtained in the
Assay,calculate the percentage of each impurity in the portion of Bupropion Hydrochloride taken by the formula:
100F(ri/rS),
in which
Fis the relative response factor for each impurity (see the accompanying table for values);
riis the peak response for each impurity obtained from the
Assay preparation;and
rSis the peak response for bupropion hydrochloride obtained from the
Standard preparation.The limits of impurities are specified in the accompanying table:not more than 0.3%of total unidentified impurities is found;and not more than 1.0%of total impurities is found,the results of
Test 1and
Test 2being added.
| Relative retention time |
Relative response factor (F) |
Limit (%) |
| 0.38 |
0.68 |
0.5 |
| 0.58 |
0.96 |
0.2 |
| 0.71 |
2.22 |
0.1 |
| 0.78 |
0.82 |
0.1 |
| 0.92 |
0.73 |
0.2 |
| 1.14 |
|
0.2a |
| 1.63 |
1.13 |
0.1 |
| 2.30 |
0.91 |
0.2 |
| 2.74 |
1.45 |
0.2 |
| all other peaksb |
1.00 |
0.1 |
|
a
The percentage is determined by direct comparison to the area of the peak for bupropion hydrochloride related compound Bobtained from the System suitability solution.
b
Except the peaks with relative retention time of 1.14.
|
Assay
Diluent
Prepare a mixture of methanol and water (1:1).
0.025M Phosphate buffer
Dissolve 6.8g of monobasic potassium phosphate in about 1900mLof water.Adjust with 1Nsodium hydroxide to a pHof 7.0,dilute with water to 2000mL,and mix.
Mobile phase
Prepare a filtered and degassed mixture of
0.025M Phosphate buffer,methanol,and tetrahydrofuran (51:39:11).Make adjustments if necessary (see
System Suitabilityunder
Chromatography á621ñ).
Standard preparation
Transfer 25mg of
USP Bupropion Hydrochloride RS,accurately weighed,to a 25-mLvolumetric flask.Dissolve in a portion of
Diluent,pipet 2.0mLof the
System suitability solutioninto the flask,dilute with
Diluentto volume,and mix.
Assay preparation
Transfer about 50mg of Bupropion Hydrochloride,accurately weighed,to a 50-mLvolumetric flask,dissolve in and dilute with Diluentto volume,and mix.
Chromatographic system (see Chromatography á621ñ)
The liquid chromatograph is equipped with a 250-nm detector and a 3.9-mm ×15-cm column that contains 5-µm packing L7.The flow rate is about 1.1mLper minute.Chromatograph the
Standard preparation,and record the peak responses as directed for
Procedure:the relative retention times are about 0.92for bupropion hydrochloride related compound Aand 1.14for bupropion hydrochloride related compound B;the resolution,
R,between bupropion hydrochloride related compound Aand bupropion hydrochloride is not less than 1.3;and the relative standard deviation for replicate injections is not more than 2.0%determined from bupropion hydrochloride and not more than 5.0%determined from bupropion hydrochloride related compound B.
Procedure
Separately inject equal volumes (about 20µL)of the
Standard preparationand the
Assay preparationinto the chromatograph,record the chromatograms,and measure the areas for the major peaks.Calculate the quantity,in mg,of C
13H
18ClNO·HCl in the portion of Bupropion Hydrochloride taken by the formula:
50C(rU/rS),
in which
Cis the concentration,in mg per mL,of
USP Bupropion Hydrochloride RSin the
Standard preparation;and
rUand
rSare the peak responses obtained from the
Assay preparationand the
Standard preparation,respectively.