Table 3 Empirical formulae and putative identification of volatile organic compounds used in the model classifying COPD and healthy subjects, grouped by principal component (PC)

1

Undecanal C₁₁H₂₂O

Hexanal C₆H₁₂O

Dodecanal C₁₂H₂₄O

Decanal C₁₀H₂₀O

Nonanal C₉H₁₈O

Pentadecanal- C₁₅H₃₀O₂

Oxirane, dodecyl- C₁₄H₂₈O

C₈H₁₄O₃ Cyclohexanol, 5-methyl-2-(1-methylethyl)-, [1R-(1à,2á,5à)]- C₁₀H₂₀O

4

Butanoic acid, 2,2-dimethyl-3-oxo-, ethyl ester C₈H₁₄O₃

Pentanoic ac C₅H₁₀O₂

Furan,2-pentyl C₉H₁₄O