Progress toward the Quantitative Analysis of PAHs Adsorbed on Soot by Laser Desorption/Laser Ionization/Time-of-Flight Mass Spectrometry.
Ex situ analyses of substances extracted from flames provide useful albeit mostly qualitative information on the formation process of soot and on the impact of exhausts on the environment. An experimental setup based on the coupling of laser desorption, laser ionization and time-of-flight mass spectrometry (LD/LI/ToF-MS) is presented in past works as an alternative means to more traditional techniques like gas chromatography (GC) to characterize the polycyclic aromatic hydrocarbons (PAHs) content of soot. In this paper, we go one step further in the understanding of the laser desorption/laser ionization dynamics and propose a combined experimental/simulation approach: we estimate the limit of detection of LD/LI/ToF-MS as low as [0.2, 2.8] fmol per laser pulse and we make quantitative predictions on the concentration of PAHs desorbed from soot. In particular, external calibration with model samples where PAHs are adsorbed on black carbon at known concentrations allows us to link the concentration of PAHs desorbed and detected by photoionization ToF-MS to the concentration of PAHs adsorbed on soot. The comparison of data obtained from the analysis of flame sampled soot with standard commercial GC-MS run in parallel validates the approach and defines limits and potentialities of both techniques.
Laboratoire de Physico-Chimie des Processus de Combustion et de l'Atmosphère (PC2A), UMR CNRS 8522, Université de Lille Sciences et Technologies , 59655 Villeneuve d'Ascq Cedex, France.
Alessandro
A
Faccinetto
Laboratoire de Physique des Lasers, Atomes et Molécules (PhLAM), UMR CNRS 8523, Université de Lille Sciences et Technologies , 59655 Villeneuve d'Ascq Cedex, France.
Cristian
C
Focsa
Laboratoire de Physico-Chimie des Processus de Combustion et de l'Atmosphère (PC2A), UMR CNRS 8522, Université de Lille Sciences et Technologies , 59655 Villeneuve d'Ascq Cedex, France.
Pascale
P
Desgroux
Laboratoire de Physique des Lasers, Atomes et Molécules (PhLAM), UMR CNRS 8523, Université de Lille Sciences et Technologies , 59655 Villeneuve d'Ascq Cedex, France.
Michael
M
Ziskind
D000327:Adsorption; D008401:Gas Chromatography-Mass Spectrometry; D057230:Limit of Detection; D008970:Molecular Weight; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis*; D012015:Reference Standards; D053260:Soot / Q000032:analysis*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013696:Temperature
D011084:Polycyclic Aromatic Hydrocarbons; D053260:Soot