FTIR–PAS: A powerful tool for characterising the chemical composition and predicting the labile C fraction of various organic waste products

Fourier transform infrared (FT-IR) spectroscopy has been used for several years as a fast, low-cost, reliable technique for characterising a large variety of materials. However, the strong influence of sample particlesize and the inability to measure the absorption of very dark and opaque samples have made FTIR unsuitablefor many waste materials. FTIR–photoacoustic spectroscopy (FTIR–PAS) can eliminate some of theshortcomings of traditional FTIR caused by scattering effects and reflection issues, and recent advancesin PAS technology have made commercial instruments available. In this study, FTIR–PAS was used tocharacterise a wide range of organic waste products and predict their labile carbon fraction, which is normallydetermined from time-consuming assays. FTIR–PAS was found to be capable of predicting the labilefraction of carbon as efficiently as near infrared spectroscopy (NIR) and furthermore of identifying thecompounds that are correlated with the predicted parameter, thus facilitating a more mechanisticinterpretatio