CHARACTERIZATION OF ORGANIC CONSTITUENTS OF ENVIRONMENTAL FILMS BY GC/MS

Abstract

The work of this thesis focuses on the further characterization of organic films that develop on the exterior and interior surfaces of windows in urban and rural areas. Previous work by our group has shown that these organic films contain organic contaminants (PAH, PCBs, OC pesticides, etc.), and air particulate material. Simulated precipitation experiments have shown that the organic film is easily washed off and that these contaminants enter surface waters, ultimately finding their way into sediments in rivers, lakes and oceans. Samples of organic films on windows were collected at numerous sites in the Toronto area between July 2000 and July 2001. Previous work led to the quantification of over 85 target analytes within these film samples including, n-alkanes, n-alkanoic acids, n-alkanoic diacids, unsaturated alkanoic acids, aromatic carboxylic acids and resin acids. Crude methanol extracts of these film samples were derivatized (MeONH2*HCl in pyridine, 37°C, 90 min. followed by N-trimethylsilyl-N-methyltrifluoroacetamide (MSTFA), 37°C, 30 min.) and analyzed by GC/MS in full scan EI+ mode. Twenty seven compounds were positively identified with authentic standards, showing excellent matches to mass spectra and retention index values. These compounds included sugars (arabinose, glucose, fructose, sucrose, trehalose), sugar alcohols (xylitol, pinitol, quebrachitol, inositols), acids (glyceric, benzoic, fumaric, succinic, malic, adipic, azelaic) and a number of other unidentified derivatives. A total of 103 unique peaks were observed in 12 window film samples. It appears that these compounds are of plant origin owing to the identification of plant sterols, β-sitosterol and stigmastanol. In addition, the wood combustion marker, levoglucosan, was identified in all but one film sample. The patterns of polar compounds identified in these films are similar to recent findings of these substances in air particulate. The profiles of these polar compounds in three Hamilton PM10 samples were similar to literature reports. The contribution of these newly identified compounds to the film exceeds or greatly exceeds the contribution of all previously identified chemical substances. There remains a significant amount of unidentified material in these films. The importance of these films lies in their pivotal role in the sequestering, transport and fate of organic contaminants in urban environments.