Comprehensive methodology for semi-volatile organic compound determination in ambient air with emphasis on polycyclic aromatic hydrocarbons analysis by GC-MS/MS.

ABSTRACT

Polycyclic aromatic hydrocarbons are air pollutants that affect the human health and the environment, and their accurate determination in outdoor and indoor environments is important. This study presents a methodology for sampling and analysis of semi-volatile compounds in ambient air with emphasis on the polycyclic aromatic hydrocarbons, collected with low-volume pumps (4.8 m3) in unconditioned solid phase extraction cartridges (Isolute ENV+). Sampling in SPE cartridges with low-volume pumps allows the collection of both gas and particulate phase compounds in indoor as well as outdoor environments, and reduces the number of extraction steps required as well as the solvent volume used for extraction. Analysis of the 16 US-EPA priority PAHs after extraction was conducted by GC-MS/MS with recoveries of the PAHs 40-118 %. No breakthrough was detected during sampling. Moreover, the methodology includes storage test to assess the conservation of PAHs in the SPE cartridges in heat-sealable Kapac bags; simulating transport from sampling sites to laboratory, and storage under room, cold and frozen conditions at different time-intervals, up to 3 months after sampling. The results showed that concentration levels remained constant across various storage time intervals and temperatures, with naphthalene and acenaphthylene being the only exceptions, showing high blank levels for the first and losses at room temperature for the later. The method quantification limits, including sampling, storage and GC-MS/MS analysis ranged from 2000 pg m-3 for naphthalene and 300 pg m-3 for phenanthrene to less than 20.0 pg m-3 for higher molecular and less volatile PAHs, such as benzo[a]pyrene (LOQ = 8.0 pg m-3). The feasibility of the method was tested by sampling indoors under urban background air conditions, showing individual PAH concentrations 4 to 10 times higher than their method quantification limits.