Comprehensive two-dimensional gas chromatography coupled to high-resolution time-of-flight mass spectrometry and simultaneous nitrogen phosphorous and mass spectrometric detection for characterization of nanoparticles in roadside atmosphere

A method is described for characterization of size-resolved particles including the nanoparticles fraction with a diameter of 29–58 nm in roadside atmosphere. The method is based on thermal desorption (TD) of a sample followed by comprehensive two-dimensional gas chromatography (GC × GC) with novel detection capabilities, including high resolution time-of-flight mass spectrometry (HRTOF-MS) and simultaneous detection with a nitrogen phosphorous detector (NPD) and a quadrupole mass spectrometer (qMS). Increased selectivity with the GC × GC–HRTOF-MS allows a group type separation of a selected chemical class, e.g. oxygenated polycyclic aromatic hydrocarbons (oxy-PAHs), using mass chromatography with a 0.05 Da wide window in the complex sample matrix. Also, exact mass measurements provide candidate elemental compositions as well as NIST library search results for tentative identifications of 50 compounds. Moreover, the simultaneous detection with the NPD and the qMS elucidate the presence of 15 nitrogen-containing compounds. Quantitative analysis of selected PAHs in several size-resolved particles was also performed by use of the TD–GC × GC–qMS with limited scan range. The method showed good linearity (r2 > 0.988) and high sensitivity (limit of quantification: <10 pg) for most of the target PAHs. The concentration of PAHs per particulate matter (PM) mass in nanoparticles was considerably higher than those of larger size of particles with a diameter of >102 nm.