The speciation of polar organic compounds provides animportant contribution to our understanding of carbonaceousaerosol. Oxygenated organic compounds are present in allemission sources including vehicles, wood combustion,cooking, etc., and may be formed during atmospherictransformation processes of primary emissions. Thereforequantitation of these compounds is important forcharacterization of both rural and urban environments.However, these compounds do not chromatograph well due totheir high boiling point, thermal instability and molecularinteractions with chromatographic columns. To address theseanalytical challenges, a silylation method has been developedto analyze 100 semi-volatile polar organic compounds manyof which are unique for specific emission sources. Rather thantwo derivatization steps for carboxylic acids and hydroxylatedcompounds, we report a single derivatization which can bedone for both of these functional groups using bis(trimethylsilyl)trifluoroacetamide (BSTFA) and 1%trimethylchlorosilane (TMCS). This derivatization performswell on hydroxyl groups, phenolic compounds, and carboxylicacid groups in the complex sample matrix of ambient andsource samples. The range of compounds analyzed by thismethod includes: levoglucosan, methoxylated phenolderivatives, methoxylated carboxylic acid derivatives, resinacids, and alkanoic and aromatic carboxylic acids. Thisanalytical method was compared to derivatization ofcarboxylic acids by diazomethane using separate fractions ofsamples. Results from the analysis of trimethylsilyl (TMS)derivatives have been compared to the results of methyl esterderivative analysis for separate fractions of 30 winter ambientsamples with a biomass combustion influence. Wood smokesamples were used in this comparison due to the highprevalence of polar organic species emitted in the combustionof biomass. In addition, these samples provide a realisticsample matrix for derivatization. We have found goodagreement for most compounds between the twoderivatization methods, however some compounds have beenfound to be different. These differences are due to hydroxylgroup derivatization by BSTFA +1% TMCS, which is notpossible with diazomethane. The derivatization greatlyenhances the thermal stability and volatility, thus providing animprovement in calibration response linearity and detectionlimits. Results of this experiment provide data for evaluationof the two polar organic speciation derivatization methods.