ANALYSIS OF NITROPOLYCYCLIC AROMATIC HYDROCARBONS IN FINE PARTICULATE MATTER BY MATRIX-ASSISTED LASER DESORPTION/IONIZATION TIME-OF-FLIGHT MASS SPECTROMETRY USING [Fe.sub.3][O.sub.4]/ZIF-8 MAGNETIC NANOCOMPOSITES AS MATRIX

Core-shell magnetic metal organic nanocrystals were synthesized and used as matrix for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Four nitropolycyclic aromatic hydrocarbons (nitro-PAHs) were successfully detected by using negative-ion MALDI-TOF MS without background interference. Furthermore, the magnetic nanocomposites (MNCs) coated with zeolitic imidazolate framework-8 (ZIF8) showed excellent adsorption and enrichment capacity, and can be isolated with a magnet and directly spotted on the stainless steel plate for MALDI measurement. It was also analyzed nitro-PAHs in PM2.5 samples using the ZIF8-coated magnetic nanocomposite as adsorbent and matrix.