Soot　is　ubiquitous　and　has　large　detrimental　effects　on　climate,　air　quality,　and　human　health.　However,　identification　of　soot　in　carbonaceous　media　is　very　challenging　due　to　its　nanoscale　carbon　nature　and　complex　sources.　Due　to　the　shortage　in　the　methodology,　until　now,　the　fate　and　health　effect　of　soot　particles　after　inhalation　are　still　poorly　understood.　Here,　we　report　a　new　method　for　label-free　identification,　quantification,　and　imaging　of　soot　particles　in　complex　media　based　on　laser　desorption/ionization　mass　spectrometry　fingerprinting.　We　found　that　soot　particles　from　different　origins　and　with　different　morphologies　showed　highly　consistent　mass　spectral　fingerprints　deriving　from　peak　ratios　of　small　carbon　cluster　anions　(C-2(-)-C-10(-)),　which　enabled　both　accurate　quantification　of　soot　in　fine　particulate　matter　(PM2.5)　samples　and　label-free　imaging　of　soot　particles　in　biological　media.　By　using　this　technique,　we　tracked　and　imaged　the　suborgan　distribution　of　soot　particles　in　mice　after　exposure　to　PM2.5.　The　results　showed　that　the　lung　is　the　main　target　organ　for　short-term　inhalation　exposure　to　soot　particles.　This　study　helps　to　better　understand　the　inhalation　toxicology　of　soot　and　also　provides　a　practical　novel　methodological　platform　for　identification,　tracing,　and　toxicological　studies　of　elemental　carbon-based　nanomaterials.