Do you have some suggests for Tadalafil impurities in USP ?

[s544186414]

I'm following the procedure of USP about the Tadalafil organic impurities.
In the below control and situation:
Mode : LC
Wavelength : 285 nm
Flow rate : 1.0 mL/min
Injection volume : 20 micro-liter
Column : 4.6-mm X 25-cm; 5-micrometer packing L7

I don't know which peak is we-wanted.
Do you have any suggest or spectrum for me to referring?
Thanks.

[dap]

Hello.
I wish USP & EP both provide harmonized monographs: https://extranet.edqm.eu/4DLink1/pdfs/chromatos/2606.pdf
I made a year ago raw material QC according to EP so spectra are also available if sill required.

[hossam kamal]

[Note— The relative retention times for tadalafil and the 6R ,12aS diastereomer of tadalafil are about 1.0 and 1.03, respectively. ]

from this i think tadalafil peak is the first peak and it diasteriomer is the second

[HPLC chemist]

Not very good chromatography. Capacity factor should be at least 2. What are your chromatographic condition? Do you have a resolution requirement in your system suitability acceptance criteria?