Thermal desorption – comprehensive two-dimensional gas chromatography coupled with tandem mass spectrometry for determination of trace polycyclic aromatic hydrocarbons and their derivatives

We developed a highly sensitive method for determination of polycyclic aromatic hydrocarbons (PAHs) and their derivatives (oxygenated, nitrated, and methylated PAHs) in trace particulate samples by using thermal desorption followed by comprehensive two-dimensional gas chromatography coupled with tandem mass spectrometry (TD–GC × GC–MS/MS) with a selected reaction monitoring mode. The sensitivity of TD–GC × GC–MS/MS was greater than that of TD–GC–HRMS and TD–GC × GC–QMS by one or two orders of magnitude. The instrumental detection limits were 0.03–0.3 pg (PAHs), 0.04–0.2 pg (oxygenated PAHs), 0.03–0.1 pg (nitrated PAHs), and 0.01–0.08 pg (methylated PAHs). For small amounts (10–20 μg) of standard reference materials (SRMs 1649a and 1650b, urban dust and diesel exhaust particles, respectively), the values measured by using TD–GC × GC–MS/MS agreed with the certified or reference values within a factor of two. Major analytes were quantified successfully by TD–GC × GC–MS/MS from diesel exhaust nanoparticles (18–32 nm) and accumulation-mode particles (100–180 nm) from an 8-L diesel engine with no exhaust after-treatment system. The PAH profiles differed among driving conditions but they did not differ markedly among the particle sizes.