K. De Braekeleer et al., Determination of the end point of a chemical synthesis process using on-line measured mid-infrared spectra, APPL SPECTR, 54(4), 2000, pp. 601-607
The orthogonal projection approach (OPA), principal component analysis (PCA
), and multivariate curve resolution alternating least-squares (MCR-ALS) ar
e applied to detect the end point of an organic synthetic process monitored
on-line by mid-infrared spectroscopy. The OPA dissimilarity criterion and
the PCA plot are useful to follow the changes in the on-line measured spect
ra and to detect regions where a steady state of the synthesis is obtained.
MCR-ALS is applied to obtain semi-quantitative information during the synt
hesis by analyzing the steady-state regions simultaneously. The concentrati
ons of the components in the different steady-state regions are calculated
with respect to their concentration in a reference steady-state region, cho
sen from the OPA dissimilarity and PCA plots.