Pholcodine Imp G

[Justyna B]

Has anyone done related substances test in 522 EP monograph for pholcodine monohydrate. I am experiencing difficulties in eluting imp G from Reference solution D; I am using EP CRS standard for identification Y0001865. I am using Phenomenex Luna Phenyl Hexyl 2.7u 4.6mm 7.5 cm column. I have absolutely no peaks eluting past pholcodine on this column and according to EDQM I should have 3 peaks with imp G about 4.2 RRT. Diluent and MP I have made as per monograph. Any ideas?

Thank you

[JMB]

Two questions here,

1. Does your chromatogram otherwise match that of the EP ?
2. Is your column brand new, or well used?

Regards,
JMB

[Justyna B]

Yes, otherwise chromatography matches EP. Retention times a bit shifted but column was not new. I have ordered pristine Kinetex Phenylhexyl and waiting for result.