Bio-oil composition

Bio-oil samples are analyzed with an Agilent 7890A gas chromatography system (GC) coupled with a mass spectrometer MS 5975C-VLMSD. The GC is equipped with a 624 capillary column, which works with helium as gas carrier. The bio-oil samples are highly diluted in acetone (ca. 10 % bio-oil and 90 % acetone) before the injection in the GC-MS that occurs through an autosampler. 1 µL of sample is injected for each analysis, whose run time was about 118 minutes. The column is heated according to the following temperature program: 4 minutes at 45 °C, heating up to 235 °C with a heating rate of 3 °C/min and 50 minutes at 235 °C. The sample is injected in “split mode” and carried by a flux of helium of 1.8 mL/min. The detector is set to scan a range of m/Z between 35 and 350; the lower limit is set to detect small species like acetic acid while avoiding causing too much baseline noise.

Bio-oil compounds identification is carried out by matching the obtained spectra with the National Institute of Standards and Technology (NIST) library. The quantification of representative compounds is carried out with the Agilent MassHunter Quantitative Analysis (Quant My-Way) software. The calibration curve for each compound is obtained with standard solutions in acetone at weight concentrations between 1% and 0.01% (except for acetic acid, whose calibration range is between 2% and 0.4%); each calibration curve results in a R2 index >0.99. Fluoranthene is added as Internal Standard (IS) at a concentration of 0.025 wt. %.