RESUMO
An on-line, inlet-based trimethylsilyl (TMS) derivatization technique was optimized and evaluated for quantitative analysis of mono- and dicarboxylic acids. The technique involves co-injection of sample and reagent followed by gas-phase formation of TMS derivatives and analysis by gas chromatography with flame ionization detection. Derivatization efficiencies were determined by comparing measured and theoretical effective carbon numbers and used to optimize the technique with respect to experimental parameters. For analysis of C5-C17 monocarboxylic acids and C2-C10 dicarboxylic acids under optimized conditions, average derivatization efficiencies were > or = 94%, average measurement uncertainties were < or = 5%, and detection limits were approximately 2 ng. The technique was applied to the analysis of carboxylic acids generated from the ozonolysis of cyclic alkenes in a smog chamber.