Journal of Chromatography A, 1253 (2012) 154–163 Contents lists available at SciVerse ScienceDirect Journal of Chromatography A j our na l ho me p ag e: www.elsevier.com/locate/chroma A one-step method for priority compounds of concern in tar from former industrial sites: Trimethylsilyl derivatisation with comprehensive two-dimensional gas chromatography C. Gauchotte-Lindsay a,∗ , P. Richards a , L.A. McGregor a , R. Thomas b , R.M. Kalin a a David Livingstone Centre for Sustainability, Department of Civil and Environmental Engineering, University of Strathclyde, Graham Hills Building, 50 Richmond Street, Glasgow, UK b Parsons Brinkerhoff, Queen Victoria House, Redland Hill, Bristol, UK a r t i c l e i n f o Article history: Received 10 May 2012 Received in revised form 28 June 2012 Accepted 29 June 2012 Available online 6 July 2012 Keywords: Comprehensive two-dimensional gas chromatography Environmental forensics Oxygenated species Coal tar phenols Trimethylsilyl derivatisation Manufactured gas plant a b s t r a c t 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 experi- ments, 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. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Tar is a by-product of manufactured gas plants (MGPs) and when released in the subsurface it forms non-aqueous phase liquids (NAPLs). Tar is a common occurrence at MGPs sites, some of which are severely affected. Tar dense NAPL (DNAPL) pollution is a major challenge for environmental remediation [1–4]. For simplicity a list of 16 US EPA priority polycyclic aromatic hydrocarbon (PAH) pollu- tants, which constitute a large proportion of the tars, is often cited as the suite of compounds for risk assessment and characterisation of tar contamination [4]. The complex and broad range of com- ponents within tars, however, also includes aliphatic compounds, phenols, cresols, and some, such as 2,4-dimethylphenol and other phenolic compounds are also listed as priority pollutants by the US EPA [5], yet are generally not quoted in the study of pollution at former MGP sites. Tar predominantly contains PAH species and oxygen, sulphur and nitrogen-PAHs [6–9], which exhibit typical pyrogenic homol- ogous relative concentrations, i.e. the less alkylated congeners are more abundant than the more alkylated ones. Although the harsh ∗ Corresponding author. Tel.: +44 0141 548 3902; fax: +44 0141 553 2066. E-mail address: caroline.gauchotte-lindsay@strath.ac.uk (C. Gauchotte-Lindsay). conditions of pyrolysis processes used at MGPs remove a large pro- portion of coal source-attributable chemicals, an understanding of the reaction of coal chemicals to pyrolysis can provide information regarding the source-attributable chemicals for MGP processes. It is believed that the composition of sulphur and nitrogen-PAHs in tar largely reflects those present in the parent coal, but with some temperature-dependent alteration [10–12]. Oxygen contain- ing compounds in tar, however, are likely to be more defined by the MGP pyrolysis process and present potential as forensic mark- ers. Ether linkages in coal frameworks are readily broken under pyrolytic conditions, yielding phenolic fragments. These undergo secondary reactions by free radical chemistry supported by the phenoxy radical, producing a range of chemicals from PAHs, cyclic alkanes, furans and ketones, as well as other phenolic species [13–15]. The chemical nature of the coal, the pyrolysis tempera- ture, the shape and type of retort, catalysis by retort surfaces and inorganic coal components affect the reactions rates and mecha- nisms. Recently, we demonstrated that the production of phenols and alkylphenols was significantly different between vertical and horizontal retort types [16]. Post tar formation alterations such as fractionation or dis- tillation processes for the recovery of chemicals of value can significantly alter the nature of tar NAPLs. These processes include simple distillation of boiling point fractions such as light oil, cre- osote and pitch, crystallisation of naphthalene, base precipitation 0021-9673/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.chroma.2012.06.093