The root mean square error of cross validation (RMSECV) for the different esters 1, amines 2, TBD and the formed amide products 3 were between 18 -68 mM, 30 -214 mM, 9 -50 mM, and 12 -42 mM, respectively. In most dynamic flow experiments, the relative error for the mass balance of ester and amine was below 10%, which is within the uncertainty of the PLS model. In almost all experiments a higher error in mass balance was observed for TBD. Predictions for the amine typically had more noise compared to product and ester predictions. This might be explained by limited characteristic bands in the spectrum (only two bands observed in the fingerprint region below 800 cm -1 ) for the amine substrates.