Extraction of preservatives from injectables prior to HPLC

[lee7]

Hi

I'm currently working with an injectable which I plan to assess with various preservative systems (benzyl alcohol, phenol and methyl/propyl parabens). The target concentration of the preservatives is much higher than that of the active ingredient and interferes with its analysis (RP-HPLC). I'll be able to improve this separation by adjusting the gradient however, ideally I'd like to "clean up" my samples prior to analysis.

The real problem is that the related substances method is a chiral analysis and I am looking for advice on how to remove/reduce the preservatives (without affecting the acitve ingredient) as they are likely to destroy the stationary phase of my column.

any suggestions would be welcome

thanks

[sassman]

It would help if you tell us what the active ingredient is. Cleanup method will be different for different substances.

[lee7]

sorry - i did mean to include more info

The active ingredient is a small aromatic molecule (MWt < 500), with similar polarity to the preservatives. The API and 4 of its potential degradants contain a quatenery amine group which lends itself to cation exchange SPE. Unfortunately, two other degradants contain n-oxide groups which will not be retained in this way.

thanks