At-line characterisation of compounds evolved during biomass pyrolysis by solid-phase microextraction SPME-GC-MS

At-line sampling by solid phase microextraction (SPME) followed by GC-MS analysis was investigated as a fast analytical method to identify and quantify the compounds evolved during intermediate pyrolysis of biomass. A 75 μm carboxen/polidimethylsiloxane (CAR/PDMS) coated fiber in retracted configuration was inserted at-line during pyrolysis at 500 °C with a bench scale fixed bed pyrolyzer of different biomass substrates, lignocellulosic feedstock, agricultural wastes, animal residues and algal biomass. The molecular composition resulting from SPME sampling was compared to the chemical composition of collected pyrolysis liquid, which included the aqueous and organic phase (bio-oil). The storage capacity of the SPME fiber was tested 48 and 96 h after sampling under air atmosphere and vacuum-packed plastic bags. The SPME-GC-MS profiles could be utilized to gather information on the characteristics of pyrolysis process, such as the efficiency of vapor condensation.