25th Croatian meeting of chemists and chemical engineers, Poreč, 2017.
Chemometric analysis of IR spectra: Who needs the HPLC?
Kemometrijska analiza IR spektara: Kome treba HPLC?
Dražen Čavužić, Ozren Wittine
PLIVA Hrvatska d.o.o., Zagreb, Croatia
E-mail: [email protected]
The aim of this study was to assess the possibility of kinetic parameters estimation for the
succinimide substitution reaction only by chemometric analysis of IR spectra acquired during
in-situ measurements, without the need for prior instrument calibration, sampling or any
other analytical technique, like HPLC.
Measurements were performed in-situ, at 100 °C, in 100 ml reaction vessel by
measuring IR spectra of melted reaction mixture during 25 hours, using process FT-IR
spectrometer equipped with optical fibers and diamond ATR probe.
To determine kinetic parameters from spectroscopic data, IR spectra were analysed
by a number of chemometric methods, including Principal Component Analysis (PCA),
Evolution Factor Analysis (EFA) and Multivariate Curve Resolution (MCR) by Alternate Least
Squares regression (ALS), alone and in combination with kinetic mathematical models of
different complexity levels.
Reaction yield estimated by simultaneous ALS and the highest complexity level
kinetic model fits was very close to experimentally obtained yield (91% vs 89%) which
validated the adopted approach.
concentration profile, k1 = 340.292, k2 = 0.0404928, k3 = 0.000295764
1
0.9
0.8
equivalents
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
200
400
600
800
time / min
1000
1200
1400
Figure1. Concentration profiles estimated by simultaneous ALS and the highest complexity level kinetic model
fits. Colours: red and blue are for reactants, pink - product, black– impurity, green– intermediate, cyan–
catalyst. Smooth lines are kinetic model fit results, dotted curves are ALS fit results.