Table 4. Py-GC/MS Relative Abundance of Structural Features within ¹²C/¹³C Wheat Straw (WS) and ¹²C/¹³C Lignin Isolates (LIGpure) on the Basis of Molar Peak Area^a.

	12C-WS	13C-WS	12C-LIGpure	13C-LIGpure
H	36.3 ± 2.0	41.1 ± 1.7	22.4 ± 2.1	25.5 ± 3.3
G	47.9 ± 2.1	45.1 ± 1.5	52.4 ± 1.5	49.7 ± 3.6
S	15.7 ± 0.7	13.9 ± 0.4	25.2 ± 0.7	24.8 ± 0.9
S/G	0.3	0.3	0.5	0.5
unsub.	21.6 ± 1.6	18.5 ± 0.5	13.9 ± 0.5	13.5 ± 0.6
methyl	4.1 ± 0.2	3.8 ± 0.2	13.3 ± 1.0	11.9 ± 0.4
ethyl	2.0 ± 0.2	1.6 ± 0.1	2.7 ± 0.2	2.5 ± 0.3
vinyl	49.1 ± 2.4	52.4 ± 2.0	28.1 ± 2.1	30.2 ± 3.4
Cα-Ob	4.4 ± 0.2	5.0 ± 0.5	9.5 ± 0.2	10.4 ± 0.3
Cβ-Oc	2.9 ± 0.3	2.2 ± 0.1	4.6 ± 0.1	4.7 ± 0.3
Cγ-Od	9.9 ± 0.5	10.9 ± 0.3	20.3 ± 1.2	19.8 ± 3.6
misc.e	6.0 ± 0.2	5.5 ± 0.4	8.9 ± 0.4	8.0 ± 0.3

^aStructural classification is shown in Table 1. Average and standard deviation of triplicates. Not corrected for relative response factors.

^bC_α-oxygen.

^cC_β-oxygen.

^dC_γ-oxygen.

^emiscellaneous.