Measurements of gas-phase inorganic and organic acidsfrom biomass fires by negative-ion proton-transferchemical-ionization mass spectrometry

摘要

Emissions from 34 laboratory biomass fires were investigated at the combustionfacility of the U.S. Department of Agriculture Fire Sciences Laboratory in Missoula,Montana. Gas-phase organic and inorganic acids were quantified using negative-ionproton-transfer chemical-ionization mass spectrometry (NI-PT-CIMS), open-path Fouriertransform infrared spectroscopy (OP-FTIR), and proton-transfer-reaction massspectrometry (PTR-MS). NI-PT-CIMS is a novel technique that measures the mass-to-charge ratio (m/z) of ions generated from reactions of acetate (CH_3C(O)O~-) ions withinorganic and organic acids. The emission ratios for various important reactive acidswith respect to CO were determined. Emission ratios for isocyanic acid (HNCO), 1,2and 1,3-benzenediols (catechol, resorcinol), nitrous acid (HONO), acrylic acid,methacrylic acid, propionic acid, formic acid, pyruvic acid, and glycolic acid weremeasured from biomass burning. Our measurements show that there is a significantamount of HONO in fresh smoke. The NI-PT-CIMS measurements were validated bycomparison with OP-FTIR measurements of HONO and formic acid (HCOOH) and withPTR-MS measurements of HCOOH.