ASTM D6209

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.

5.2 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.

1. 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.

1.4 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.

2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.