Test 1: Impurities eluting before tamsulosin
Solution pH 2.0
Dissolve 8.7 mL of perchloric acid (70%) and 3.0 g of sodium hydroxide in 1900 mL of water. Adjust to a pH of 2.0 with 1 N sodium hydroxide, and add sufficient water to make 2000 mL.
Mobile phase 1
Prepare a mixture of
Solution pH 2.0 and acetonitrile (7:3). Make adjustments if necessary (see
System Suitability under
Chromatography
621
).
Diluent
Use Mobile phase 1.
Test solution
Dissolve an accurately weighed portion of Tamsulosin Hydrochloride in Diluent to obtain a solution having a known concentration of about 5.0 mg per mL.
Standard solution
Dilute a portion of the Test solution with Diluent to obtain a solution having a known concentration of 10 µg per mL.
System suitability solution
Dissolve 5 mg of Tamsulosin Hydrochloride and 0.01 g of propylparaben in 20 mL of Diluent. Dilute 2 mL of this solution with Diluent to make 20 mL.
Chromatographic system (see Chromatography
621
The liquid chromatograph is equipped with a 225-nm UV detector and a 4.6-mm × 15-cm column that contains 5-µm packing L1. The column temperature is maintained at 40

. The flow rate is about 1.3 mL per minute. Chromatograph the
System suitability solution, and record the peak responses as directed for
Procedure: the elution order is tamsulosin hydrochloride followed by propylparaben, and the resolution between tamsulosin and propylparaben is not less than 12. Chromatograph the
Standard solution: the relative standard deviation for six replicate injections is not more than 4%.
Procedure
Inject equal volumes (about 10 µL) of the
Standard solution and the
Test solution into the chromatograph, record the chromatograms for about 1.5 times the retention time of tamsulosin, and measure the peak responses. Calculate the percentage of any individual impurity in the portion of Tamsulosin Hydrochloride taken by the formula:
100 (CS / CT)(rU / rS)
where
CS and
CT are the concentrations, in mg per mL, of tamsulosin in the
Standard solution and the
Test solution, respectively;
rU is the area of each peak eluted before tamsulosin obtained from the
Test solution; and
rS is the peak area of tamsulosin obtained from the
Standard solution. Not more than 0.10% of each impurity is found.
[NoteIf present, the des-ethoxy impurity and the methoxy impurity eluting at the relative retention time of about 0.8 are not separated by this method and should be integrated together to determine conformance. (The des-ethoxy impurity is 2-methoxy-5-[(2
R)-2-[(2-phenoxyethyl)amino]propyl]benzenesulfonamide, and the methoxy impurity is 2-methoxy-5-[(2
R)-2-[[2-(2-methoxyphenoxy)ethyl]amino]propyl]benzenesulfonamide.) Not more than 0.20% of the sum of the des-ethoxy and methoxy impurities is found.
] The reporting level for impurities is 0.05%.
Test 2: Impurities eluting after tamsulosin
Solution pH 2.0, Diluent, Test solution, and Standard solution
Prepare as directed in Test 1 for Related compounds.
Mobile phase 2
Prepare a mixture of
Solution pH 2.0 and acetonitrile (1:1). Make adjustments if necessary (see
System Suitability under
Chromatography
621
).
Chromatographic system (see Chromatography
621
The liquid chromatograph is equipped with a 225-nm detector and a 4.6-mm × 15-cm column that contains 5-µm packing L1. The column temperature is maintained at 40

. The flow rate is about 1.0 mL per minute. The relative standard deviation of six replicate injections of the
Standard solution is not more than 4%. Use a column that meets the resolution requirements of
Test 1 for
Related compounds.
Procedure
Inject a volume (about 10 µL) of the
Standard solution and the
Test solution into the chromatograph, record the chromatograms for at least 5 times the retention time of tamsulosin, and measure the peak responses. Calculate the percentage of any individual impurity in the portion of Tamsulosin Hydrochloride taken by the formula:
100 (CS / CT)(rU / rS)
where
CS and
CT are the concentrations, in mg per mL, of tamsulosin in the
Standard solution and the
Test solution, respectively;
rU is the area of each peak eluted after tamsulosin obtained from the
Test solution; and
rS is the peak area of tamsulosin obtained from the
Standard solution. Not more than 0.10% of each impurity is found. The reporting level for impurities is 0.05%. Not more than 0.2% of total impurities is found, the results for
Test 1 and
Test 2 being combined.