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 PAHCompound
(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 применения1.1 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.