Table 2.

List of 19 VOCs investigated in this study for the derivation of predictive equations for CLASS.

Order	Group	Compoundsa	Short name	Carbon numbers	MW (g mol−1)	Density (g cm−3)	Boiling point (°C)	Formula	CAS number
1	Aldehyde	Acetaldehyde	AA	2	44.1	0.785	20.2	C2H4O	75-07-0
2		Propionaldehyde	PA	3	58.1	0.798	46–50	C3H6O	123-38-6
3		Butyraldehyde	BA	4	72.1	0.805	74.8	C4H8O	123-72-8
4		Isovaleraldehyde	IA	5	86.1	0.797	90	C5H10O	590-86-3
5		n-Valeraldehyde	VA	5	86.1	0.81	103	C5H10O	110-62-3
6	Aromatic	Benzene	B	6	78.11	0.878	80.1	C6H6	71-43-2
7		Toluene	T	7	92.14	0.866	110.6	C7H8	108-88-3
8		Styrene	S	8	104.2	0.906	145	C8H8	100-42-5
9		p-Xylene	p-X	8	106.2	0.865	138.35	C8H10	106-42-3
10		m-Xylene	m-X	8	106.2	0.865	139	C8H10	108-38-3
11		o-Xylene	o-X	8	106.2	0.88	144.4	C8H10	95-47-6
12		Propionic acid	PPA	3	74.1	0.99	141	C3H6O2	79-09-4
13	Carboxylic	n-Butyric acid	BTA	4	88.1	0.958	163.5	C4H8O2	107-92-6
14	(volatile fatty acid)	i-Valeric acid	IVA	5	102	0.925	175–177	C5H10O2	503-74-2
15		n-Valeric acid	VLA	5	102	0.938	186-187	C5H10O2	109-52-4
16	Ketone	Methyl ethyl ketone	MEK	4	72.11	0.805	79.64	C4H8O	78-93-3
17		Methyl isobutyl ketone	MIBK	6	100.2	0.802	117-118	C6H12O	108-10-1
18	Alcohol	Isobutyl alcohol	i-BuAl	4	74.12	0.801	107.89	C4H10O	78-83-1
19	Ester	n-Butyl acetate	BuAc	6	116.2	0.881	127	C6H12O2	123-86-4

^a18 compounds except for AA are used to calculate the projected response factor (RF) for model compounds.