The cream formulation contains terbinafine hydrochloride, lidocaine, L-menthol, dipotassium glycyrrhizate, diethylene glycol monoethyl ether, isopropyl myristate, carbomer 940, sodium docusate, parabens, and other excipients.
We are attempting to analyze terbinafine-related genotoxic impurities, such as N‑nitroso terbinafine degradant and N‑nitroso terbinafine impurity A. However, due to matrix effects caused by the excipients, the recovery is very low (approximately 10%).
Are there any effective methods to reduce matrix effects in this case? Any advice would be greatly appreciated.
Best way would be to weigh every single excipient separately and spike with reference solution.
With this you could see what exactly is causing your bad recoveries and with the knowledge you could try to get rid of it. If polarity of excipient and analyte are quite different, then perfoming a liquid/Liquid partition would be an quick and easy solution.