Table 2.

Summary of concentration of ‘glycerol monoesters', ‘free resin acids’ and ‘neutrals’ in GEWR

	GEWR manufactured from P. palustris and P. elliottii	GEWR manufactured from P. halepensis and P. brutia
Glycerol monoesters	HPLC–MS (glycerol monoabietate): 0.1%	HPLC–MS (glycerol monoabietate): 0.01%
	GC&GC–TOF MS: 0.46%	GC&GC–TOF MS: < 0.1%
Free resin acids	Average: 3.5%	Average: 2.6%
Neutrals	Average: 14.6%	Average: 14.4%

GEWR: glycerol esters of wood rosin; HPLC–MS; high‐performance liquid chromatography–mass spectrometry; GCxGC‐TOF MS: gas chromatography coupled with high‐resolution time‐of‐flight mass spectrometry.