The amine pump was also turned off during the standard addition process to investigate if an intermediate species between the ester and the TBD could be observed, with or without passing through the heated reactor coil (Valve 1 in position A or B). In each case, no significant decrease in the ester concentration was observed, implying that the active intermediate does not form (in appreciable quantities) in the absence of an amine nucleophile. This is in agreement with previous reports, whereby the formation of an acylated TBD intermediate is reversible and has only been isolated in reaction with specific lactone substrates. Two methods of building a PLS model were investigated: (1) automated PLS model generation in Python and (2) manual PLS model generation in PEAXACT (by an operator). Typically, 12 different concentration levels from the standard addition were used as training data for the PLS model. Both approaches provide similar results, however the automated approach reduced the PLS model generation time from an hour (depending on experience of the user) to a few minutes. Applying a first derivative pretreatment to the raw spectra provided improved results compared to second derivative or no derivative. Multiple PLS models were generated for the different substrate combinations with both processing approaches. The obtained results (ranks for the PLS model, RMSEs and mass balances) from both approaches provided similar results and are explained in detail in the supporting information.