| 1 |
gas chromatography (GC)-undetectable |
very heavy tars cannot be
detected by GC |
subtracting
GC-detectable
tar from total gravimetric tar |
| 2 |
heterocyclic aromatics |
heteroatoms, highly water-soluble
compounds |
pyridine,
phenol, cresols,
quinoline |
| 3 |
light aromatic
(1 ring) |
usually,
a light HC with
a single ring does not pose a problem regarding condensability and
solubility |
toluene,
ethylbenzene, xylenes,
styrene |
| 4 |
light PAH (2–3 rings) |
two- and three-ring compounds
condense at low temperatures, even at very low concentrations |
indene, naphthalene, biphenyl,
fluorene, anthracene |
| 5 |
heavy PAH (4–7 rings) |
larger than three-ring,
these components condense at high temperatures at low concentrations |
fluoranthene, pyrene, chrysene,
perylene, coronene |
