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 5-µm packing L7. The flow rate is about 1 mL per minute. Chromatograph the
Test solution, and record the peak areas as directed for
Procedure: the relative retention times are about 0.79 for 4-(8-chloro-11-fluoro-6,11-dihydro-5
H-benzo[5,6]cyclohepta[1,2-
b]pyridin-11-yl)-1-piperidinecarboxylate ethyl and 1.0 for loratadine. Chromatograph the
Standard solution, and record the peak areas of the main peak as directed for
Procedure: the relative standard deviation for replicate injections is not more than 4.0%.
Procedure
Separately inject equal volumes (about 50 µL) of the
Test solution and the
Standard solution into the chromatograph, record the chromatograms, and measure all of the peak area responses in the
Test solution and the peak area of the main peak in the
Standard solution. Calculate the percentage of each impurity in the portion of Tablets taken by the formula:
2500(C/L)(ri / rS),
in which
C is the concentration, in mg per mL, of
USP Loratadine RS in the
Standard solution; L is the labeled quantity, in mg, of loratadine in each Tablet taken;
ri is the peak area response for each impurity in the
Test solution; and
rS is the peak area response of loratadine in the
Standard solution: not more than 0.2% of 4-(8-chloro-11-fluoro-6,11-dihydro-5
H-benzo[5,6]cyclohepta[1,2-
b]pyridin-11-yl)-1-piperidinecarboxylate ethyl is found; not more than 0.1% of any other individual impurity is found; and the sum of all impurities, other than 4-(8-chloro-11-fluoro-6,11-dihydro-5
H-benzo[5,6]cyclohepta[1,2-
b]pyridin-11-yl)-1-piperidinecarboxylate ethyl, is not more than 0.1%.