A one-step method for priority compounds of concern in tar from former industrial sites: Trimethylsilyl derivatisation with comprehensive two-dimensional gas chromatography

A dense non-aqueous phase liquid sample formed by release of coal tar into the environment was derivatised by trimethylsilylation using the reagent N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) and extracted in hexane using accelerated solvent extraction. This procedure enables comprehensive extraction of an extensive suite of organic compounds from tar, which has not previously been described. Comprehensive two dimensional gas chromatography coupled to time of flight mass spectrometry (GC×GC–TOFMS) was used for the analysis of the sample for concurrent evaluation of –OH functional group-containing compounds along with aliphatics, polycyclic aromatic hydrocarbons and other typical tar compounds normally determined via classic gas chromatography. Using statistically designed experiments, a range of conditions were tested for complete recovery of four different surrogates. The robustness and repeatability of the optimised derivatisation/extraction method was demonstrated. Finally, more than a hundred and fifty derivatised compounds were identified using mass spectra elucidation and GC×GC logical order of elution.

► We developed a pre-extraction trimethylsilylation method for coal tar DNAPL samples.
► The method was optimised using a CCC experimental design.
► 165 –OH containing compounds were extracted and their TMS esters tentatively identified.
► Hydroxy polycyclic aromatic heterocycles and carboxylic acids were identified.
► The logical order of elution in GC×GC was used to help identification of compounds.