An easy and reliable method for syringyl: guaiacyl ratio measurement

Lignin structure elucidation is one of the main targets for biorefinery related research. Because of its complexity, obtaining reproducible results in a straight-forward way is very important. One of the values that is used to compare different lignins is the syringyl:guaiacyl (S/G) ratio, which has been measured in different ways. The most reliable result is obtained for nitrobenzene oxidation, but this involves a complex process. In this work, the S/G ratios measured by pyrolysis-gas chromatography mass spectrometry (py-GCMS) and heteronuclear single quantum coherence-nuclear magnetic resonance (HSQC-NMR) spectroscopy were compared with attenuated total reflection infrared (ATR-IR) spectroscopy results to establish a reliable, quick, and simple method for the measurement. To achieve this, two mathematical models were applied with multivariate data analysis software. A partial least squares regression model for py-GCMS gave the best result.