Pyrolysis-gas chromatography-mass spectrometry Kováts retention index of pyrolysis products of lignocellulosic materials

•Calibration of Kováts Retetion Index for Py-GC-MS analysis.•Peak identification based on Kováts RI.•Structural Certification of unknown compounds using Kováts RI of standard compounds in a GC-MS system.

Pyrolysis - gas chromatography - mass spectrometry (Py-GC-MS) is a common hyphenated analytical technique for the characterisation of lignocellulosic materials, but such natural polymers generate highly complex total ion current pyrograms. Recently, normalised retention time and automated deconvolution of chromatograms have been shown to be a viable method for analyses containing a large number of peak components. However, the use of Kováts retention index (RI) has not been examined in Py-GC-MS for lignocellulosic materials. In this study, we test the use of linear alkane polyethylene pyrolysis products to calibrate the Kováts RI for pyrolysis products of lignocellulosic materials in a Py-GC-MS system. Linear alkane polyethylene pyrolysis products yield a correct Kováts RI, which means the method has the advantages of being able to apply the NIST/EPA/NIH mass spectra library database for peak identification. In addition, using such an approach, Kováts RI of standard compounds calibrated using a GC-MS system may be used for structural certification of unknown pyrolysis products due to the similarities of RI calibration in both systems (GC-MS x Py-GC-MS).