GC/MS-FID analysis of BSTFA derivatized polar components of diesel particulate matter (NBS SRM-1650) extract

Abstract

Hydroxy and acid compounds, present in the polar HPLC fraction number 8 from the NBS-SRM 1650 (diesel particulate extract) were derivatized with N,O-bis(trimethylsilyl)-trifluoroacetamide (BSTFA) to form the trimethylsilane (TMS) derivatives. This improved the gas-chromatographic separation to give an improved characterisation using GC-MS. TMS derivatives were only observed in the acid extract of an aliquot of HPLC fraction number 8 which had undergone an acid-base fractionation. A number of previously unidentified compounds in fraction 8 could be characterised using mass spectroscopy. Ion mass chromatograms, recorded at m/z 73, 89 and 147 were correlated with the total ion current (TIC) to identify derivatized compounds. Only single, two and three ring derivatized aromatics were observed. The compounds identified in this polar fraction of the extract included p-nitrophenol, benzoic acid, hydroxy-benzoic acids, hydroxy-benzaldehyde, hydroxy-phthalimide, benzene dicarboxylic acids, naphthalene dicarboxylic acids, anthracene/phenanthrene dicarboxylic acids and, for some of these, the C1 to C3 alkyl homologues. Several methyl esters were also observed including biphenyl dimethyl ester and benzene trimethyl ester.