Quantitative Fourier Transform Infrared spectroscopic investigation of humic substance functional group composition

Infrared (IR) spectroscopy has been widely used for the structural investigation of humic substances. Although Fourier Transform Infrared (FTIR) instrumentation has been available for sometime, relatively little work with these instruments has been reported for humic substances. IR spectroscopy, like other optical spectroscopies, is a quantitative technique that follows the Beer-Lambert Law. An internal standard FTIR technique is described that allows the quantitative comparison of specific IR absorption bands among different humic substances. The technique provides compositional information on the functional groups present in humic substances. The FTIR technique produces information similar to C-13 nuclear magnetic resonance (NMR) spectroscopy. However, the FTIR method requires less sample quantity and spectral acquisition times are significantly smaller than required for C-13 NMR. This new technique extends the previous qualitative IR spectroscopic studies of humic substances to a quantitative method for the investigation of humic substance structure and composition. (C) 1999 Elsevier Science Ltd. All rights reserved.