Quantification of lignin in synthetic mixtures of xylan and cellulose powders by photoacoustic spectroscopy

The UV-Vis photoacoustic (PA) spectroscopy was demonstrated suitable for sensitive, direct and non-destructive study of lignin in synthetic cellulose/xylan mixtures. The PA spectra recorded in the 250–550 nm wavelength range show no characteristic peak; however the amplitude of the PA signal tends to increase for higher contents of lignin in the mixture. The quantification of lignin in cellulose/xylan mixtures was accomplished by analysing PA signals obtained at 300 and 400 nm; the limits of detection (LOD) are 1.8% (at 300 nm) and 0.4% (at 400 nm).