Air pollution -POSTER SESSION

Secondary organic aerosol (SOA) is a significant constituent of airborne fine particles. A multistep derivatization method was developed, optimized, and validated for the determination of organic compounds in the atmospheric aerosol with mono- and multi-functional species, with GC/MS. The first step includes the alkylation of the carbonyl (C=O) moieties using o-methylhydroxylamine hydrochloride as the derivatization reagent. The second step refers to the conversion of carboxylic acids to methyl ester derivatives using TMSD/methanol or BF3/methanol. Finally, alcohols are converted to trimethylsilyl ethers with BSTFA+ 1% TMCS. The use of TMSD/methanol as the derivatization reagent in step 2 is preferred for the procedure, achieving higher sensitivity. Additionally, BF3/MeOH was ineffective at converting some mono/dicarboxylic acids and species with more than 2-OH moieties. The derivatization procedure in stage 3 was optimized yielding the appropriate reaction temperature and time, while in stage 2 yielding the appropriate amounts of the derivatization reagents. The method was validated for twenty-two compounds which are possible SOA tracers. Detection limits ranged from 0.31 to 0.98 ng m-3 and recoveries from 73.5% to 108%. The method was applied to field samples from rural and industrial areas with concentration levels ranging from below limits of detection to 42 ng m-3.