Chemical characterization of size-selected nanoparticles emitted by a gasoline direct injection engine: Impact of a catalytic stripper

This work combines laser desorption/ionization mass spectrometry (L2MS) and advanced statistical techniques to reveal the impact of a catalytic stripper (CS) on the chemical composition (at the molecular level) of a gasoline direct injection engine exhaust, and follow the evolution of size-dependent chemical characteristics over the whole particles size range (10?560 nm). The gas phase and polydisperse particles making up the exhaust are separated and sampled on distinct substrates using an original homebuilt two-filter system, while size-selected particles are collected using a cascade impactor and separated into 13 different size bins (smallest diameters 10?18 nm). We demonstrate that a fine molecular-level characterization of the exhaust particulate matter is necessary to assess the effect of the CS, especially for the smallest ultra-fine particles carrying the largest volatile fraction.