Airborne Polycyclic Aromatic Hydrocarbons (PAHs) (Thailand)
To investigate the gas particle distribution and particle size dependency of semi-volatile organic compound such as PAHs, a combination of an Andersen low volume cascade impactor followed by a glass tube containing XAD-2 polymer beads with a specific dimension was used. The XAD-2 absorbent tube was designed by referring to the level of pressure drop across the sampler in order to maintain constant flow rate during the sampling period to insure the proper aerodynamic cut-off diameter for 50% collection efficiency of the sampler. The dimensionof the tube is illustrated in the attached figure. Teflon coated glas fiber filters were used to collect particles on each of the impactor stages as well as particles that were too small to be collected by the impactor. XAD-2 was used to adsorb gas-phase constituents.
Sector: Other Technologies n.e.c.
Country: India
Area of Application: The sampling system designed in this study is suitable for the investigation of airborne PAHs (with molecular weights of 202 and above) in the tropical climate since even at sampling temperatures of 35 deg C, none of the listed PAHs was traceable in the second layer of the XAD-2 adsorbent tube.
Keywords: Polycyclic Aromatic Hydrocarbons, PAHs
Advantages: The advantage of impactor sampling is to provide minimal contact of collected particulate matter with the air stream so that the particle blow-off effect can be kept to a minimum. Furthermore, cascade impactor sample provides particles over the inhalable size range. Beside, T60A20 appears to have superior filtering qualities because of its reduced surface activity. This may contribute to a redued degradation of collected PAHs during sampling and storage. XAD-2 adsorbent, as well, has several advantages un terms of collection efficiency, good recovery of adsorbed compounds and minimal degradation during storage.
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