Measurements were collected on either on compact FTIR spectrometer (Alpha II, Bruker Ltd. Canada) controlled by computer software (OPUS, Bruker, USA) or a research grade spectrometer (Nicolet iS50, Thermo Fisher Scientific, USA) with a KBr beam splitter and a nitrogen-cooled MCT detector, and controlled by software (OMNIC, Thermo Fisher Scientific, USA). In both cases a purge gas generator was used to limit atmospheric interference. All spectra were acquired with 32 co-additions and a 4 cm -1 spectral resolution, except where otherwise stated. Spectrofluidic devices were interfaced with an ATR spectroscopy microfluidic assay accessory (ASMAA) for spatial-selective measurements which is described elsewhere. Data analysis was carried out using open source software (Quasar, Orange, ). 11