PARAFAC modeling of fluorescence excitation−emission spectra for rapid assessment of compost maturity

Assessment of compost maturity is crucial for achieving high quality compost in order to guarantee its marketability. In this context, a novel technique that combines fluorescence excitation–emission matrices (EEMs) with parallel factor (PARAFAC) analysis to assess compost maturity is presented. A total of 60 fluorescence EEMs of composts were successfully decomposed into a three-factor model using PARAFAC analysis. Components 1 [excitation/emission (Ex/Em) wavelengths = (230, 330)/410] and 2 [Ex/Em wavelengths = (250, 350)/450] were attributable to humic-like and fulvic-like substances, whereas component 3 [Ex/Em wavelengths = (220, 280)/340] belonged to protein-like substances. Pearson correlation analysis between the common maturity indices and log scores of three components demonstrated that components 1 and 3 are more suitable to assess compost maturity than component 2. These results reveal that EEM–PARAFAC could be applied as a valuable tool for assessing compost maturity, given its high sensitivity and selectivity.