Table 3 List of possible marker compounds for the different class comparisons determined via chemometric analysis, including a categorization of the loading values. All compound names are tentative assignments based on NIST 20 spectral comparison and literature RI values. For diagnostic fragment ions and match scores, see Supplementary Table S1. RT: Retention time; AHC: aromatic hydrocarbons, HC: hydrocarbons, MT: monoterpenes, ST: sesquiterpenes; RI: Kovats retention index for non polar columns according to the pherobase database, ALB: Anoplophora glabripennis, HT: Healthy tree, SC: Saperda carcharias, CC: Cossus cossus. Loading values (LV): LV \(<{0.005}:~\vartriangle\), LV \(<{0.010}:~\vartriangle \vartriangle\), LV \(\ge {0.010}:~\vartriangle \vartriangle \vartriangle\), LV \(>{-0.005}:~\triangledown\), LV \(>{-0.010}:~\triangledown \triangledown\), LV \(\le {-0.010}:~\triangledown \triangledown \triangledown\), –: no differences in comparison.
Peak no. | RT, min | Class | CAS-no. | Compound | RI | ALB-HT | SC-HT | CC-HT | ALB-SC | ALB-CC | SC-CC |
|---|---|---|---|---|---|---|---|---|---|---|---|
1 | 3.3 | – | – | Unknown | – | \(\vartriangle \vartriangle \vartriangle\)/\(\triangledown\) | – | – | \(\vartriangle \vartriangle \vartriangle\)/\(\triangledown \triangledown \triangledown\) | \(\vartriangle \vartriangle \vartriangle\) | – |
2 | 3.8 | AHC | 108-88-3 | Toluene | 762 | \(\vartriangle \vartriangle\)/\(\triangledown\) | \(\vartriangle \vartriangle\)/\(\triangledown\) | \(\vartriangle \vartriangle\)/\(\triangledown \triangledown\) | \(\vartriangle\)/\(\triangledown\) | \(\vartriangle\) | \(\vartriangle \vartriangle\)/\(\triangledown\) |
3 | 4.1 | HC | 589-53-7 | 4-Methyl heptane | 770 | \(\vartriangle\) | – | – | \(\vartriangle\)/\(\triangledown\) | \(\vartriangle\) | \(\triangledown\) |
4 | 4.4 | HC | 111-65-9 | n-Octane | 800 | \(\vartriangle\)/\(\triangledown\) | \(\vartriangle\)/\(\triangledown\) | \(\vartriangle\)/\(\triangledown\) | – | \(\vartriangle\) | – |
5 | 4.7 | HC | 66-25-1 | Hexanal | 800 | \(\vartriangle \vartriangle \vartriangle\)/\(\triangledown\) | \(\vartriangle \vartriangle\)/\(\triangledown \triangledown \triangledown\) | \(\vartriangle \vartriangle\)/\(\triangledown \triangledown\) | \(\vartriangle \vartriangle\)/\(\triangledown \triangledown \triangledown\) | \(\vartriangle \vartriangle\)/\(\triangledown\) | \(\vartriangle \vartriangle\)/\(\triangledown\) |
6 | 5.5 | HC | 19549-87-2 | 2,4-Dimethyl- 1-heptene | 830 | \(\vartriangle\) | – | – | \(\vartriangle\) | \(\vartriangle\)/\(\triangledown\) | – |
7 | 6.4 | HC | 111-84-2 | n-Nonane | 900 | \(\vartriangle\) | \(\vartriangle\) | \(\vartriangle\)/\(\triangledown\) | \(\vartriangle \vartriangle \vartriangle\) | – | \(\vartriangle \vartriangle \vartriangle\)/\(\triangledown \triangledown\) |
8 | 6.8 | AHC | 100-42-5 | Styrene | 893 | \(\triangledown\) | \(\vartriangle \vartriangle\) | \(\vartriangle\) | – | – | – |
9 | 7.1 | MT | 7785-70-8 | \(\alpha\)-Pinene | 934 | \(\triangledown \triangledown\) | \(\vartriangle \vartriangle \vartriangle\) | \(\vartriangle\) \(\vartriangle \vartriangle\) | \(\vartriangle\) | \(\vartriangle\) | – |
10 | 9.1 | MT | 13466-78-9 | 3-Carene | 1011 | \(\vartriangle\) | – | – | \(\vartriangle\) | \(\vartriangle\) | – |
11 | 9.5 | MT | 138-86-3 | Limonene | 1047 | \(\vartriangle \vartriangle \vartriangle\)/\(\triangledown\) | – | \(\triangledown \triangledown\) | \(\vartriangle \vartriangle\)/\(\triangledown \triangledown\) | \(\vartriangle \vartriangle \vartriangle\)/\(\triangledown \triangledown\) | \(\vartriangle \vartriangle \vartriangle\)/\(\triangledown\) |
12 | 10.4 | HC | 1120-21-4 | Undecane | 1100 | – | – | \(\triangledown\) | – | \(\vartriangle\) | – |
13 | 11.1 | HC | 124-19-6 | Nonanal | 1104 | \(\vartriangle \vartriangle\)/\(\triangledown\) | \(\vartriangle \vartriangle\)/\(\triangledown\) | \(\vartriangle \vartriangle\)/\(\triangledown\) | \(\vartriangle\)/\(\triangledown\) | \(\vartriangle \vartriangle\) | \(\triangledown\) |
14 | 12.5 | HC | 112-31-2 | Decanal | 1209 | \(\vartriangle\)/\(\triangledown\) | \(\triangledown\) | – | – | – | – |
15 | 13.5 | – | – | Unkown | – | – | – | \(\triangledown\) | – | \(\triangledown\) | \(\vartriangle\) |
16 | 14.1 | HC | 629-50-5 | Tridecane | 1300 | \(\vartriangle\)/\(\triangledown\) | \(\vartriangle \vartriangle\)/\(\triangledown\) | \(\vartriangle\)/\(\triangledown\) | – | – | – |
17 | 15.0 | – | – | Unknown | – | – | \(\vartriangle\) | \(\vartriangle\) | – | – | – |
18 | 15.2 | – | – | Unknown | – | \(\vartriangle\) | – | – | – | \(\vartriangle\) | – |
19 | 15.5 | ST | 5989-08-2 | \(\alpha\)-Longipinene | 1351 | \(\triangledown\) | \(\vartriangle \vartriangle\) | \(\vartriangle \vartriangle\) | – | – | – |
20 | 15.8 | ST | 22469-52-9 | Cyclosativene | 1368 | \(\vartriangle\) | \(\vartriangle\)/\(\triangledown\) | \(\vartriangle\)/\(\triangledown\) | \(\vartriangle\) | \(\vartriangle\) | \(\vartriangle\) |
21 | 15.9 | ST | 3856-25-5 | Copaene | 1376 | \(\vartriangle\) | \(\triangledown\) | – | \(\triangledown\) | – | – |
22 | 16.3 | ST | 87-44-5 | Caryophyllene | 1428 | \(\vartriangle\)/\(\triangledown\) | \(\triangledown\) | – | \(\vartriangle\)/\(\triangledown \triangledown\) | \(\vartriangle\) | \(\vartriangle \vartriangle\)/\(\triangledown\) |
23 | 17.4 | HC | 629-62-9 | Pentadecane | 1500 | \(\vartriangle \vartriangle\)/\(\triangledown\) | \(\vartriangle \vartriangle\)/\(\triangledown \triangledown\) | \(\vartriangle \vartriangle\)/\(\triangledown \triangledown\) | \(\vartriangle\) | \(\vartriangle\) | – |
24 | 17.7 | ST | 495-60-3 | \(\alpha\)-Zingiberene | 1495 | \(\vartriangle\) | – | – | \(\vartriangle\)/\(\triangledown\) | \(\vartriangle\) | – |
