Table 1.

Results of PLS regression between molecular weight and inter‐unit abundances as determined by GPC and 2D HSQC NMR spectroscopy, respectively, for the 54 lignin samples and their ATR‐FTIR using 1st derivative pre‐processing.

Entry	Unit	Range	Num. LV[a]	Variance captured [%]		RMSEC[b]	RMSECV	RE[c] [%]	R 2 Cal.	R 2 CV[d]
				X (FTIR)	Y (Cal.)
1	M n	4626	7	94	94	260	400	8.7	0.94	0.85
2	log(M n)	0.95	7	94	98	0.034	0.059	6.2	0.98	0.94
3	M w	29 984	10	96	92	1500	3000	10	0.92	0.70
4	log(M w)	1.7	6	93	94	0.091	0.13	7.6	0.94	0.88
5	D	5.03	5	89	72	0.69	1.0	20	0.72	0.44
6	β‐O‐4	34	4	85	94	1.8	2.8	8.2	0.94	0.85
7	β‐5	10	4	86	88	0.74	1.1	11	0.88	0.75
8	β‐β	3.9	5	90	85	0.33	0.53	14	0.85	0.61

[a] Num. LV=number of latent variables. [b] RMSEC=root mean squared error of calibration. [c] RE=RMSECV/range. [d] Venetian blinds with 10 splits and 1 sample per split; values reported to 2 significant figures; see Figure S2 for the associated regression vectors.