Journal of Chromatography A, 1257 (2012) 131–140 Contents lists available at SciVerse ScienceDirect Journal of Chromatography A jou rn al h om epage: www.elsevier.com/locat e/chroma Quantitative analysis of crude and stabilized bio-oils by comprehensive two-dimensional gas-chromatography  Marko R. Djokic a , Thomas Dijkmans a , Guray Yildiz b , Wolter Prins b , Kevin M. Van Geem a,∗ a Laboratory for Chemical Technology, Ghent University, Technologiepark 918, 9052 Zwijnaarde, Belgium b Department of Biosystems Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium a r t i c l e i n f o Article history: Received 31 March 2012 Received in revised form 8 July 2012 Accepted 9 July 2012 Available online 28 July 2012 Keywords: Crude and hydrotreated bio-oil Comprehensive 2D GC Time of flight mass spectrometry Split/splitless and cold-on column injector a b s t r a c t Bio-oils produced by fast pyrolysis of lignocellulosic biomass have proven to be a promising, clean, and renewable energy source. To better assess the potential of using bio-oils for the production of chemicals and fuels a new comprehensive characterization method is developed. The combination of the analyical power of GC × GC–FID and GC × GC–TOF-MS allows to obtain an unseen level of detail for both crude and hydrotreated bio-oils originated from pine wood biomass. The use of GC × GC proves to be essen- tial to capture the compositional differences between crude and stabilized bio-oils. Our method uses a flame ionization detector to quantify the composition, while GC × GC–TOF-MS is used for the qualitative analysis. This method allows quantification of around 150 tentatively identified compounds, describing approximately 80% of total peak volume. The number of quantified compounds in bio-oils is increased with a factor five compared to the present state-of-the-arte. The necessity of using multiple internal standards (dibutyl ether and fluoranthene) and a cold-on column injector is also verified. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Biomass fast pyrolysis is an emerging clean and renewable source of energy, fuels and chemicals [1]. Fast pyrolysis of biomass is a thermal decomposition process that occurs in the absence of oxygen, with quick biomass decomposition and rapid vapor condensation, to convert biomass mainly into a liquid product (known as bio-oil) with a yield as high as 75 wt%. Techno-economic analysis of the biomass fast pyrolysis process has emphasized the potential of bio-oil for fuels but in particular for chemi- cals [2]. Chemically, bio-oils are complex mixtures of water and hundreds of organic compounds that belong to acids, aldehydes, ketones, alcohols, esters, anhydrosugars, furans, phenols, guaiacols, syringols, nitrogen containing compounds, as well as large molec- ular oligomers (holocellulose-derived anhydro-oligosaccharides and lignin-derived oligomers). Pyrolysis liquids contain negligi- ble amounts of ash, and have a volumetric energetic density 5–20 times higher than the original biomass. However, the oil is acidic in nature, polar and not miscible with conventional crude oil. In addi- tion, it is unstable, as some (re)polymerization of organic matter  Presented at the 12th International Symposium on Hyphenated Techniques in Chromatography and Hyphenated Chromatographic Analyzers (HTC-12), Bruges, Belgium, 31 January–3 February 2012. ∗ Corresponding author. Tel.: +32 478573874/32 92645597; fax: +32 92645824. E-mail address: kevin.vangeem@Ugent.be (K.M. Van Geem). in the oil causes an increase in viscosity over time. Therefore, so- called hydrodeoxygenation (HDO) is commonly applied to reduce the oxygen content of crude bio-oils and its acidity [3]. In this pro- cess oxygen containing compounds are converted into aliphatic and aromatic compounds using hydrogen in the presence of a hetero- geneous catalyst such as a Ni/Mo supported catalyst, as well as a Pt supported on mesoporous zeolite [4–7]. In order to get improved insight into the (catalytic) fast pyrolysis process and the following HDO stabilization, as well to better assess the potential of using bio-oils as (drop-in) biofuels, a detailed chem- ical analyses of products of both processes are necessary. Various analytical techniques have been combined for obtaining a global analysis of bio-oils, such as chromatographic techniques (GC–FID, TLC, HPLC) [8], pyrolysis GC–MS, elemental analysis, acid number determination, capillary electrophoresis, Fourier transform infra- red spectroscopy, 1 H, 13 C and 31 P NMR spectroscopy [6,8–12]. Hyphenated techniques such as comprehensive two-dimensional gas chromatography (GC × GC) have recently gained a lot of atten- tion to analyze bio-oils. Because of the two-dimensional separation a significantly increased chromatographic resolution is achieved, which is crucial for identification and quantification of these com- plex mixtures. The use of a GC × GC in combination with time of flight mass spectrometry (TOF-MS) and flame ionization detector (FID) is a very powerful and versatile analytical tool for fast and detailed bio-oil analysis. However, to the best of our knowledge no proper analytical method has been developed that allows obtain- ing a detailed quantitative analysis of bio-oils. Quantification of 0021-9673/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.chroma.2012.07.035