Polynuclear Aromatic Hydrocarbons
Polynuclear aromatic hydrocarbons (PAH’s or PNA’s) can be collected as either coal tar pitch volatiles (CTPV) or as semi-volatile organic compounds. Collection as CTPV requires that samples be collected on glass fiber filters which are then analyzed gravimetrically as the benzene soluble non-volatile residue. CTPV samples should be collected at 2 liters per minute (LPM) for a total of between 480 and 960 liters, and the filters should be transferred to amber glass vials with PTFE lined closures immediately after sampling. Samples analyzed for CTPV can often subsequently be analyzed for up to 5 individual PAH’s as listed in the OSHA 58 method. For samples which exceed the PEL for CTPV (0.2 mg/m3), the following five PAHs are recommended: phenanthrene, anthracene, pyrene, chrysene and benzo-alpha-pyrene.
If the coal tar pitch result is not required, the recommended collection media for PAHs is the OVS-2 tube. The OVS-2 tube consists of a 13mm glass fiber filter backed by XAD-2 beads, improving the collection of the more volatile of the PAHs. The samples should be collected at 1 LPM for a total of between 240 and 480 liters.
The full list of PAHs which can be analyzed include: phenanthrene, anthracene, pyrene, chrysene, benzo-alpha-pyrene, naphthalene, fluoranthene, benzo-alpha-anthracene, perylene, 3-methyl-cholanthene and coronene.