Significance and Use
5.1 Polycyclic aromatic hydrocarbons (PAH) as defined by this test method are compounds made up of two or more fused aromatic rings.
5.4 Two- and three-ring PAH are typically present in urban air at concentrations ranging from 10 to several hundred nanograms per cubic metre (ng/m3); those with four or more rings are usually found at concentrations of a few ng/m3 or lower.
5.5 PAH span a broad spectrum of vapor pressures (for example, from 1.1 × 10–2 kPa for naphthalene to 2 × 10–13 kPa for coronene at 25°C). Table 1 lists some PAH that are frequently found in ambient air. Those with vapor pressures above about 10–8 kPa will be present in the ambient air substantially distributed between the gas and particulate phases. This test method will permit the collection of both phases. However, particulate-phase PAH will tend to be lost from the particulate filter during sampling due to desorption and volatilization.
| Compound | Formula | Molecular | Melting | Boiling | Vapor |
| Naphthalene | C10H8 | 128.18 | 80.2 | 218 | 1.1 × 10 –2 |
| Acenaphthylene | C12H8 | 152.20 | 92-93 | 265-280 | 3.9 × 10–3 |
| Acenaphthene | C12H10 | 154.20 | 90-96 | 278-279 | 2.1 × 10–2 |
| Fluorene | C13H10 | 166.23 | 116-118 | 293-295 | 8.7 × 10–5 |
| 9-Fluorenone | C13H8O | 180.21 | 84 | 341.5 | ca.10 –5 |
| Anthracene | C14H10 | 178.24 | 216-219 | 340 | 3.6 × 10 –6 |
| Phenanthrene | C14H10 | 178.24 | 96-101 | 339-340 | 2.3 × 10–5 |
| Fluoranthene | C16H10 | 202.26 | 107-111 | 375-393 | 6.5 × 10–7 |
| Pyrene | C16H10 | 202.26 | 150-156 | 360-404 | 3.1 × 10–6 |
| Cyclopental[cd]pyrene | C18H10 | 226.28 | ca. 275? | — | ca. 10–7 |
| Benz[a]anthracene | C18H12 | 228.30 | 157-167 | 435 | 1.5 × 10–8 |
| Chrysene | C18H12 | 228.30 | 252-256 | 441-448 | 5.7 × 10–10 |
| Retene | C18H18 | 234.34 | 101 | 390 | ca. 10–6 |
| Benzo[b]fluoranthene | C20H12 | 252.32 | 167-168 | 481 | 6.7 × 10–8 |
| Benzo[k]fluoranthene | C20H12 | 252.32 | 198-217 | 480-481 | 2.1 × 10–8 |
| Perylene | C20H12 | 252.32 | 273-278 | 500-503 | 7.0 × 10–10 |
| Benzo[a]pyrene | C20H12 | 252.32 | 177-179 | 493-496 | 7.3 × 10–10 |
| Benzo[e]pyrene | C20H12 | 252.32 | 178-179 | 493 | 7.4 × 10–10 |
| Benzo[ghi]perylene | C22H12 | 276.34 | 275.278 | 525 | 1.3 × 10–11 |
| Indeno[1,2,3-cd]pyrene | C22H12 | 276.34 | 162-163 | — | ca. 10–11 |
| Dibenz[ah]anthracene | C22H14 | 278.35 | 266-270 | 524 | 1.3 × 10–11 |
| Coronene | C24H12 | 300.36 | 438-440 | 525 | 2.0 × 10 –13 |
5.5.1 The distribution between phases depends on ambient temperature, humidity, types and concentrations of PAH and particulate matter, and residence time in the air. PAH, especially those having vapor pressures above 10–8 kPa, may vaporize from particulate filters during sampling. Consequently, a back-up vapor trap must be used for efficient sampling.
Scope
1.1 This test method2 specifies sampling, cleanup, and analysis procedures for the determination of polycyclic aromatic hydrocarbons (PAH) in ambient air.
1.2 This test method is designed to collect both gas-phase and particulate-phase PAH and to determine them collectively.
1.3 This test method is a high-volume sampling (100 to 250 L/min) method capable of detecting PAH at sub-nanograms per cubic metre (ng/m3) concentrations with sampling volumes up to 350 m3 of air.
1.6 This test method describes a sampling and analysis procedure for PAH that involves collection from air on a combination fine-particle filter and sorbent trap and subsequent analysis by gas chromatography/mass spectrometry (GC/MS).
1.9 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. See also Section 8 for additional safety precautions.
