Applied_Spectroscopy_Practica_01_01 - 29

Kara Ali et al.
175
Figure 2. (a) Infrared spectra of the pure components Cy, H, PS, and DCE. Shaded areas indicate the spectral regions used for multivariate
analysis. (b) Infrared spectra of representative compositions in the selected spectral regions. The numerical values in the legend indicate the
approximate Cy and H percentage in the mixture.
different washing conditions, W1 and W2, were tested. The
Cy-only model was used for the precipitated paste and pellets,
where it should be the dominant solvent, while the
H-only model was used for the washed pastes. The results
are presented in Table I in terms of wt% of the relevant solvent
and percentage of spectrum fit, a parameter that indicates
how well the experimental sample spectrum is
reconstructed based on the model. An acceptable spectrum
fit value above 97% was found only for the pellets, in which a
minute quantity of H is indeed expected to be present. The
Cy content is lower in the washed pellets obtained from
W2 (1.1%) than from its W1 counterpart (1.8%), consistent
with more drastic washing conditions for W2. On the
other hand, the Cy-only model completely fails to estimate
the Cy content in the precipitated paste, where the spectrum
fit is very poor (54%) and the sum of the percentages of Cy,
PS, and DCE is far from 100%. Observation of the paste spectra
indicates that this is due to the presence of H that makes
the Cy-only model inapplicable. Similarly, the H-only model
fails to properly describe the washed pastes, with spectrum

Applied_Spectroscopy_Practica_01_01

Table of Contents for the Digital Edition of Applied_Spectroscopy_Practica_01_01