Three-Way Modelling of a Batch Organic Synthesis Process Monitored by near Infrared Spectroscopy

Multivariate monitoring by near infrared (NIR) spectroscopy of an organic synthesis as a batch process gives three-way data of the type batch number × NIR wavelength × time. The data can be analysed by three-way decomposition methods such as parallel factor analysis (PARAFAC). The batch process is the synthesis of an ester carried out by students in the laboratory. The synthesis is monitored by fibre-optic probe NIR measurement every ten minutes. The NIR spectra obtained have no distinct peaks and simply doing curve resolution on them is very difficult, but it is shown that pretreatment of the NIR spectra can lead to a good PARAFAC model and a chemical interpretation of the unique loadings obtained. The interpretation of the spectral loadings is carried out by comparison with pure chemical spectra. The data set is available from the authors.