Table 2. Results of GC-MS analysis of keruing wood extractives

Retention time (min)	Chemical name	Concentration (%)	Functional chemical structure	Corrosion inhibitor or accelerator
12.89	Coumaran	27.28	Cyclic structureO-structure	Corrosion inhibitor
21.10	Antiarol	9.57	Cyclic structureO-structure	Corrosion inhibitor
24.54	4-((1E)-3-Hydroxy-1-propenyl)-2-methoxyphenol	4.01	Cyclic structureO-structureDouble bond	Corrosion inhibitor
24.70	Methyl p-coumarate	12.11	Cyclic structureO-structureDouble bond	Corrosion inhibitor
25.55	2-Cyclohexen-1-one, 4-hydroxy-3,5,6-trimethyl-4-(3-oxo-1-butenyl)-	9.33	Cyclic structureO-structureDouble bond	Corrosion inhibitor
28.47	Elaol	5.87	Cyclic structureO-structureDouble bond	Very weak acid, corrosion accelerate
29.04	3-(2,5-Dimethoxyphenyl)-propionic acid	2.40	Cyclic structureO-structureDouble bond	Weak acid, corrosion accelerator
36.80	Hexadecanal	2.30	Aliphatic structureO-structureDouble bond	Corrosion inhibitor
49.45	γ-Sitosterol	9.86	Cyclic structureO-structureDouble bond	Corrosion inhibitor
53.40	Sitostenone	17.26	Cyclic structureO-structureDouble bond	Corrosion inhibitor

GC-MS: gas chromatograph-mass spectrometer.