Table 3: Band strengths of molecules used for integration.

Species	Vibration mode	Position	Position	A	Ref.
		m	cm-1	cm group-1
silicates	SiO str.	10	1000		a
aliphatics	CH str.	3.4	2800-3000		b
CH2 group	asym. CH2 str.	3.42	2922		c
CH3 group	asym. CH3 str.	3.38	2958		c
ketones	C=O str.	5.83	1715		d
carboxylic acids	C=O str.	5.88	1700		d
carboxylic acids	OH str.	2.77-4.35	3600-2300		e
carboxylic acid salts	COO- str.	6.3	1586		d
aromatics	ring stretch	6.2	1600		f

a Jaeger et al. (1998), in cm (SiO bond)-1. b Dartois et al. (2004), in cm (C atom)-1, based on the value for hexane  cm molec-1 dividing by 6 for the number of C atoms (see text for details). c Dartois et al. (2004), in cm (C atom)-1. d Wexler (1967). e Using area(OH str.)/area(C=O str.) and for glycolic acid (carboxylic acid) we obtain A(OH) . f Schutte et al. (1998), in cm (C atom)-1, corresponding to the average of neutral PAHs.