In situ quantitative imaging of concentration profiles of reactants and products inside a microfluidic reactor is achieved, with submicron spatial resolution with similar to mM sensitivity and on similar to ms time scales, for a given position. The label-free approach relies on quantitative vibrational spectroscopy, using Coherent Anti-Stokes Raman scattering microscopy in a spectrally resolved fashion, and is demonstrated on an elementary acid-base reaction.
J. Am. Chem. Soc.

Schafer, D., Squier, J., van Maarseveen, J., Bonn, D., Bonn, M., & Müller, M. (2008). In situ quantitative measurement of concentration profiles in a microreactor with submicron resolution using multiplex CARS microscopy. J. Am. Chem. Soc., 130, 11592–11593. doi:10.1021/ja804158n