Table 2.

Identified PAHs extracted from the AS-PAH surface

Peak	m/z	Retention time (min)	Name	Sum formula	Rings	IARC carcinogens classification	Identified by
1	128	10.867	Naphthalene	C10H8	2	2B	M
2	152	14.250	Biphenylene	C12H8	3	–	NIST
3	152	14.900	Acenaphthylene	C12H8	3	–	M
4	166	16.583	Fluorene	C13H10	3	3	M
5	178	18.867	Phenanthrene	C14H10	3	3	NIST
6	178	18.958	Anthracene	C14H10	3	3	M
7	190	20.308	Benzo[def]fluorene	C15H10	4	–	NIST
8	202	21.725	Fluoranthene	C16H10	3	3	M
9	202	22.233	Pyrene	C16H10	4	3	M
10–12	226	24.667–25.125	Cyclopenta[cd]pyrene/Benzo[ghi]fluoranthene	C18H10	5	2A 3	NIST
13	240	26.450	9H-Cyclopenta[a]pyrene	C19H12	5	–	NIST
14	252	28.225	Benzo[j]fluoranthene	C20H12	5	2B	NIST
15	276	30.775	Benzo[ghi]perylene	C20H12	6	3	NIST
16	276	30.992	Indeno[1,2,3-cd]pyrene	C20H12	6	2B	NIST
17	300	33.150	Coronene	C24H12	7	3	NIST

PAH compounds were analyzed with GC/MS and identified by reference substances (M) or by the National Institute of Standards and Technology Database (NIST). Some of the compounds are represented as isomers. A representative GC/MS chromatogram of PAHs from an AS-PAH sample is shown in Additional file 2 F. PAHs are classified by International Agency for Research on Cancer (IARC) monographs: 2A means “probably carcinogenic to humans”; 2B means “possibly carcinogenic to humans” and 3 means “not classifiable as to its carcinogenicity to humans” [90]. m/z = mass-to-charge ratio