Author: Chris A. JakoberPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
The understanding of carbonyl emissions from motor vehicles was enhanced via new chemical analysis approaches in conjunction with alternative emissions sample collection methodologies and examination of solution photolysis. High performance liquid chromatography (HPLC) with atmospheric pressure chemical ionization (APCI) ion trap mass spectrometry (ITMS) chemical analysis with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) derivatization provides additional analytical utility for characterization of carbonyl emissions from motor vehicle combustion. This is especially true for compounds containing multiple carbonyl functional groups, e.g., quinones, which are typically hindered in gas-chromatography (GC) with ITMS analysis due to the large molecular weight and lower vapor pressure of their PFBHA oximes. Carbonyl emissions from gasoline powered light-duty vehicles (LDVs) and heavy-duty diesel powered vehicles (HDDVs) operated on chassis dynamometers were measured using an annular denuder-quartz filter-polyurethane foam sampler, allowing for collection of both gas- and particle-phase emissions, in conjunction with PFBHA derivatization and chemical analysis by GC-ITMS and HPLC-APCI-ITMS. Gas- and particle-phase emissions for 39 aliphatic (C2-C14) and 20 aromatic carbonyls (C---C13) ranged from 0.1 to 2000 [mu]g L−1 fuel consumed for LDVs and 1.8 to 27000 [mu]g L−1 fuel consumed for HDDVs. Carbonyls accounted for 19% of particulate organic carbon (POC) emissions from low-emission LDVs and 37% of POC emissions from three-way catalyst equipped LDVs, but only 3.3 to 3.9% for HDDVs. These measurements identify carbonyls as one of the largest classes of compounds in particulate matter emissions from LDVs operated on chassis dynamometers to date. Nine quinones were observed from C6 to C16. This research is the first to measure gas-phase quinone emissions from motor vehicles combustion, with emissions ranging from 2 to 28,000 [mu]g L−1 fuel consumed. Eight particle-phase quinones were observed between 2 to 1600 mug L -1. Select quinones were furthered examined to assess their photolytic stability in solution, a surrogate for particle-phase behavior. Calculated quinone atmospheric lifetimes, based on aqueous photolysis, ranged from 1.7 to 28 minutes under midday, summer solstice, clear sky conditions at Davis, CA (38.6 °N). These results indicate that motor vehicle emissions of carbonyls, especially quinones given their observed toxicological implications, must be properly considered for accurate public health risk assessments.