Development of a short path thermal desorption-gas chromatography/mass spectrometry method for the determination of polycyclic aromatic hydrocarbons in indoor air

- Short-path thermal desorption eliminates the transfer line between thermal desorption device and GC instrument.
- Method has high desorption efficiency for PAHs and low residues in the analytical systems.
- Quiet low flow personal pump over 7 days provides sufficient analytical sensitivity for detecting airborne PAHs in residential indoor air.
- Residential indoor air PAHs are dominated by 3-ring PAHs besides naphthalene.

Polycyclic aromatic hydrocarbons (PAHs) are present in petroleum based products and are combustion by-products of organic matters. Determination of levels of PAHs in the indoor environment is important for assessing human exposure to these chemicals. A new short path thermal desorption (SPTD) gas chromatography/mass spectrometry (GC/MS) method for determining levels of PAHs in indoor air was developed. Thermal desorption (TD) tubes packed with glass beads, Carbopack C, and Carbopack B in sequence, were used for sample collection. Indoor air was sampled using a small portable pump over 7 days at 100 ml/min. Target PAHs were thermally released and introduced into the GC/MS for analysis through the SPTD unit. During tube desorption, PAHs were cold trapped (−20 °C) at the front end of the GC column. Thermal desorption efficiencies were 100% for PAHs with 2 and 3 rings, and 99-97% for PAHs with 4-6 rings. Relative standard deviation (RSD) values among replicate samples spiked at three different levels were around 10-20%. The detection limit of this method was at or below 0.1 μg/m3 except for naphthalene (0.61 μg/m3), fluorene (0.28 μg/m3) and phenanthrene (0.35 μg/m3). This method was applied to measure PAHs in indoor air in nine residential homes. The levels of PAHs in indoor air found in these nine homes are similar to indoor air values reported by others.