Determination of Polycyclic Aromatic Hydrocarbons in Airborne Particulate Matter by Gas ChromatographyTriple Quadrupole Tandem Mass Spectrometry

An accurate and sensitive method for the identification and the quantification of 24 polycyclic aromatic hydrocarbons (PAHs) in airborne particulate matter has been developed and validated using GC/MS/MS with a triple quadrupole analyzer. Ultrasonic extraction (USE) and pressurized liquid extraction (PLE) were evaluated. PLE was selected because it provided better recoveries and reduced treatment time and use of solvents compared to USE. Cleanup of PLE extracts was not necessary. The accuracy of the optimized method was tested using a standard reference material of urban dust (SRM 1649a). PAH recoveries were between 70 and 99 (except for naphthalene, which was lower than 20) with RSDs ranging from 2.6 to 15.3. Linearity in the range 5500 ng/mL provided R2 values higher than 0.99 for all compounds. LODs for PAHs ranged from 0.001 to 0.435 ng/mL and LOQs ranged from 0.003 to 0.757 ng/mL. The proposed method was applied to the analysis of real samples collected in the city of Almera, Spain, where some PAHs were found at levels lower than the legislated limit.

On the isolation of elemental carbon for micro-molar ¹⁴C accelerator mass spectrometry; evaluation of alternative isolation procedures, and accuracy assurance using a hybrid isotopic particulate carbon reference material

The primary objective of the research reported here has been the development of an hybrid reference material (RM) to serve as a test of accuracy for elemental carbon (EC) isotopic (14C) speciation measurements. Such measurements are critically important for the quantitative apportionment of fossil and biomass sources of ''soot'' (EC), the tracer of fire that has profound effects on health, atmospheric visibility, and climate. Previous studies of 14C-EC measurement quality, carried out with NIST SRM 1649a (Urban Dust), showed a range of results, but since the ''truth'' was not known for this natural matrix RM, one had to rely on isotopic-chemical consistency evidence (14C in PAH, EC) of measurement validity (Currie et al., 2002). Components of the new Hybrid RM (DiesApple), however, have known 14C and EC composition, and they are nearly orthogonal (isotopically and chemically). NIST SRM 2975 (Forklift Diesel Soot) has little or no 14C, and its major compositional component is EC. SRM 1515 (Apple Leaves) has the 14C content of biomass-C, and it has little or no EC. Thus, the hybrid RM can serve as an absolute isotopic test for the absence of EC-mimicking pyrolysis-C from SRM 1515 in the EC isolate of the hybrid RM, together with testing for conservation of its dominant soot fraction through the isolation procedure.