If you want to show that your actives deposit onto the hair surface or penetrate deeper into the fiber you may consider doing some active delivery studies.

FTIR Spectroscopy and Raman Spectroscopy enables us to visualize the distribution of a particular molecule or ingredient on the hair surface or in a hair cross-section.  The key advantage of FTIR and Raman imaging is that is often possible to image active delivery without needing to chemically modify, or ‘tag’, the active.  Formulations can be applied as supplied.

TRI Publications
Zhang et al (2018)