“…24,25 Initially, it was reported that PM mainly contains dry soot, SOF, sulfates, ash, and moisture. 26 Similarly, Mohankumar et al 27 proposed that PM could be divided into a soluble and insoluble organic fraction, and soot accounts for the major proportion. Liati et al 28,29 analyzed the ash chemical composition, which consisted mainly of Ca, Mg, P, Zn, S, O and minor amounts of Fe, Al and Si.…”