Значение и использование

5.1 Polycyclic aromatic hydrocarbons (PAH) as defined by this test method are compounds made up of two or more fused aromatic rings.

5.2 Several PAH are considered to be probable human carcinogens.

5.3 PAH are emitted in the atmosphere primarily through wood or fossil fuel combustion.

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.

TABLE 1 Formulae and Physical Properties of Selective PAH

Compound
(Common Name)

Formula

Molecular
Weight

Melting
Point,
°C

Boiling
Point,^A
°C

Vapor
Pressure,
kPa at
25°C

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

^A Many of these compounds sublime.

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.

5.6 Separate analyses of the filter and vapor trap will not reflect the original atmospheric phase distributions and should be discouraged.

Область применения

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.

1.4 This test method has been validated for sampling periods up to 24 h.

1.5 Precision and bias under normal conditions can be expected to be ±35 to 50 %.

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).

1.7 The range of this test method is approximately 0.05 to 1000 ng/m³ of air sampled.

1.8 The values stated in SI units shall be regarded as standard.

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.