Bio-oil (pyrolysis oil) is the liquid product of biomass thermochemical conversion. It is a dark, viscous liquid that contains the depolymerization products of hemicellulose, cellulose, and lignin. The physicochemical properties of bio-oils are determined by employing the conventional methods for fuels analysis with proper adaptations. However, the detailed composition of bio-oils in terms of analytes as well as their concentration remains ambiguous and is a challenging task for analytical chemistry. The compounds in the bio-oil range from nonpolar (e.g., hydrocarbons) to highly polar (e.g., phenolics) and from volatile (e.g., organic acids) to nonvolatile (e.g., sugar derivatives), covering a molecular weight (MW) range of about 50-2000 Da. Hence a combination of analytical techniques such as high pressure liquid chromatography, gas chromatography (GC), gel permeation chromatography (GPC), nuclear magnetic resonance spectroscopy (NMR), and Fourier transform infrared spectroscopy (FTIR) are required to determine the bio-oil's composition. Despite the significant breakthroughs of these techniques, they face limitations regarding the sample pretreatment, the incomplete separation and determination of components, and the need of multiple analyses with each method for more complete results. The development of sophisticated, comprehensive, and hyphenated chromatographic and spectrometric techniques such as GC × GC, LC × LC, high-resolution mass spectrometry (HRMS), and 2D-NMR has brought actual advancement in the field of bio-oil analysis. GC × GC and LC × LC have allowed the development of qualitative and quantitative methods for the individual determination of lower MW compounds. However, HRMS and 2D-NMR have facilitated the elucidation of the structure of the higher MW components, offering insight in the effect of pyrolysis conditions on biomass depolymerization and the possibilities for further upgrading of bio-oils.

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The composition of essential oils from twigs and needles of Balkan pine (Pinus peuce Gris.) grown in northern Greece was investigated. The compounds were identified by using GC-MS analysis. The twig oil was rich in alpha-pinene (7.38%), beta-pinene (12.46%), beta-phellandrene (26.93%), beta-caryophyllene (4.48%), and citronellol (12.48%), and the needle oil was rich in alpha-pinene (23.07%), camphene (5.52%), beta-pinene (22.00%), beta-phellandrene (6.78%), bornyl acetate (9.76%), beta-caryophyllene (3.05%), and citronellol (13.42%). The mean oil yield was 2.85% for twigs and 0. 57% for needles.

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A separation technique was developed for the characterization and identification of the nonaromatic fraction of a light and a heavy FCC feedstock (gas−oil). The separation of the paraffins was based upon the selective reaction of n-paraffins with urea and branched paraffins with thiourea. One more method based on the molecular sieves adsorption was also applied for n-paraffin separation, but the urea method was found to be more satisfactory. The total recovery of the method was about 70%. All the fractions were characterized using a system of GC/MS under the specific conditions presented in this work. The hydrocarbons in the n-paraffinic and isoparaffinic fractions were identified satisfactorily, while for the naphthenic fraction this identification was more difficult. A quantitative analysis was attempted of all the paraffinic compounds in the FCC feedstock. Using a standard sample of n-paraffins, the relative wt % concentrations of the n-paraffinic and isoparaffinic compounds were determined. For the cycloparaffins, the method of ASTM D2786 was applied and the concentrations of naphthenes were approximately estimated according to the number of rings in these compounds.