Standard Test Method for Determination of Gaseous and Particulate Polycyclic Aromatic Hydrocarbons in Ambient Air (Collection on Sorbent-Backed Filters with Gas Chromatographic/Mass Spectrometric Analysis)

Importancia y uso:

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.

(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.

Subcomité:

D22.03.02

Volúmen:

11.07

Número ICS:

13.040.20 (Ambient atmospheres)

Palabras clave:

ambient atmospheres; analysis; gas chromatography-mass spectrometry; PAH; polycyclic aromatic hydrocarbons;