Introduction
Material and methods
Raw materials
Experimental procedures
Sample preparation
Molecule | AcOH | DBN | APP | H2O |
---|---|---|---|---|
Concentration range wt.% | 7.5–32.6 | 2.7–67.4 | 0–58.4 | 0.1–75.2 |
Refractometry
Raman spectroscopy
Data analysis
Exploratory data analysis: Principal Components Analysis (PCA)
Partial least squares regression (PLS)
Results and discussion
The limitations of refractometry
Raman spectra of the liquid mixtures
Effects of H2O addition
Effects of APP addition
Principal components analysis (PCA)
PLS for the quantification of DBN, APP, AcOH and H2O in the liquid mixtures
PLS model based on the entire spectra
Component | LVs | X var% | Y var% | RMSEC, wt.% | RMSECV, wt.% | R2 | Range, wt.% |
---|---|---|---|---|---|---|---|
AcOH | 3 | 98.7 | 99.9 | 0.20 | 0.23 | 0.999 | 7.5–32.6 |
DBN | 4 | 99.1 | 99.7 | 1.73 | 2.09 | 0.992 | 2.7–67.4 |
APP | 5 | 99.6 | 99.8 | 0.81 | 1.15 | 0.998 | 0–58.4 |
H2O | 3 | 96.9 | 99.9 | 0.68 | 0.64 | 0.999 | 0.1–75.2 |
Enhancing the PLS model prediction performance through variable selection
Component | RMSEC before iPLS, wt.% | RMSEC after iPLS, wt.% | No. of intervals for minimum RMSEC |
---|---|---|---|
AcOH | 0.20 | 0.14 | 3 |
DBN | 1.73 | 0.76 | 2 |
APP | 0.81 | 0.52 | 3 |
H2O | 0.68 | 0.41 | 7 |