Assessing the chemical composition of bio-oils using FT-ICR mass spectrometry and comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry

Abstract

Bio-oils were obtained from the flash-pyrolysis of empty palm fruit bunch and pine wood chips. They were analyzed by negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI(−)-FT-ICR MS) and comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-TOFMS), in order to provide a complementary and comprehensive characterization of the bio-oils. ESI(−)-FT-ICR MS detected high-oxygen content compounds, with m/z values ranging from 150 to 700, resulting in percentages of assignable peaks higher than 80% (composed of heteroatom classes from O2 to O14 with a carbon number of C6–C27 and a double bond equivalent [DBE] of 1–14). All assignable signals showed ultrahigh resolution and accuracy mass (mean of mass error lower than 0.05ppm). Some low-oxygen content classes inaccessible by ESI-FT-ICR MS were identified by GC×GC-TOFMS (classes from O0 to O8 with a carbon number of C3–C14). The chemical characterization of the bio-oils combining the high chromatographic resolution power of GC×GC-TOFMS (detecting volatile compounds) with the high dynamic range of m/z of ESI-FT-ICR MS allowed identification of polar, volatile and nonvolatile compounds. Detailed information on the composition of these oils is very important when upgrading to second-generation biofuels and when using the oils as a base for chemicals.