Protocols and data analysis in quantitative optothermal in vivo transdermal diffusion measurements

We report the development of measurement protocols and data analysis techniques that allow the optothermal diffusion measurements of externally applied substances through human skin to be interpreted quantitatively. We present the theoretical background relating measured optothermal decay times to surface concentration, from which mass diffusion and partition coefficients can be calculated. The methods are illustrated using propylene glycol and a number of other diols as examples.