Polydopamine　nanospheres　(PDA)　were　designed　to　serve　as　a　new　substrate　for　surface-enhanced　desorption/ionization　mass　spectrometry　(SELDI-MS).　Compared　with　conventional　organic　matrices,　the　PDA　substrate　showed　superior　LDI　performance　for　analyzing　a　wide　variety　of　environmental　pollutants,　including　polycyclic　aromatic　hydrocarbons,　bisphenols,　benzophenones,　sulfonamides,　perfluorinated　compounds　and　estrogens.　Benzoapyrene　was　used　to　evaluate　the　ability　of　quantitative　analysis　and　its　corresponding　limit　of　detection　(LOD)　of　as　low　as　0.1　ng　was　achieved.　High　sensitivity　and　good　reproducibility　of　PDA-based　SELDI-MS　allowed　us　to　determine　ultratrace　PAHs　in　airborne　particulate　matters　(PM2.5),　and　the　corresponding　concentration　of　BaP　in　different　PM2.5　were　5.32,　8.97　and　9.79　ng　m-3.　Significantly,　PDA　exhibits　the　characteristics　of　simple　synthesis,　low　cost,　non-toxicity　and　less　matrix　interference,　which　provides　the　possibility　for　the　sensitive　analysis　of　organic　small　molecule　pollutants　at　low　concentrations　in　complex　environmental　samples.　This　journal　is　©　The　Royal　Society　of　Chemistry.