High-throughput prediction of eucalypt lignin syringyl/guaiacyl content using multivariate analysis: a comparison between mid-infrared, near-infrared, and Raman spectroscopies for model development

Table 2 Comparison of PLS calibration models using vibrational spectroscopy and pyrolysis molecular beam mass spectrometry

Method	SEL calibration^1,a	RMSEC^2,a	RM- SECV^3,a	R²Cal⁴	R²CV⁵	F⁶	Outliers⁷
Raman 2 ^nd deriv (19 pt) + SNV 32 scans	0.05	0.13	0.14	0.83 ± 0.02	0.81 ± 0.02	4-5	2
Raman 1 ^st deriv (7 pt) + EMSC 32 scans	0.05	0.13	0.14	0.845 ± 0.003	0.82 ± 0.01	4-5	3
Raman EMSC + 2 ^nd deriv (15 pt) 96 scans	0.05	0.13	0.14	0.83 ± 0.01	0.81 ± 0.01	5-6	2-3
Raman 2 ^nd deriv (15 pt) + SNV 96 scans	0.05	0.13	0.13	0.84 ± 0.01	0.82 ± 0.01	4-5	4-5
MIR EMSC + 2 ^nd deriv (15 pt)	0.05	0.13	0.14	0.84 ± 0.03	0.81 ± 0.03	3-4	1-2
MIR 2 ^nd deriv (17 pt) + MSC	0.05	0.13	0.14	0.82 ± 0.01	0.78 ± 0.01	3-4	1-2
MIR 2 ^nd deriv (17 pt) + SNV	0.05	0.13	0.14	0.85 ± 0.02	0.82 ± 0.03	3-4	2-3
NIR EMSC + 2 ^nd deriv (25 pt)	0.05	0.17	0.18	0.73 ± 0.01	0.681 ± 0.004	4-5	4-7
NIR 2 ^nd deriv (25 pt) + MSC	0.05	0.17	0.18	0.72 ± 0.02	0.68 ± 0.02	4-6	1-5
NIR 2 ^nd deriv (25 pt) + SNV	0.05	0.16	0.17	0.74 ± 0.01	0.70 ± 0.02	4-5	2-3

¹Standard Error of the Laboratory for the calibration data.
²Root Mean Standard Error of Calibration.
³Root Mean Standard Error of Cross-Validation.
⁴Coefficient of determination for calibration set.
⁵Coefficient of determination for full cross-validation.
⁶Average number of factors used in model construction.
⁷Number of outliers removed from calibration models.
^aAverage errors of 3 randomly generated models using data provided. Models were not statistically different.
The numbers listed parenthetically reflect the degree of Savitzky-Golay spectral smoothing.
Statistical values are the average of 3 independent models.
MIR = mid-infrared spectroscopy, NIR = near-infrared spectroscopy, EMSC = extended multiplicative scatter correction, MSC = multiplicative scatter correction, SNV = standard normal variate.

ISSN: 2731-3654