Coupling pyrolysis with mid-infrared spectroscopy (Py-MIRS) to fingerprint soil organic matter bulk chemistry - Archive ouverte HAL Access content directly
Journal Articles Journal of Analytical and Applied Pyrolysis Year : 2018

Coupling pyrolysis with mid-infrared spectroscopy (Py-MIRS) to fingerprint soil organic matter bulk chemistry


A novel method coupling pyrolysis with mid-infrared spectroscopy (Py-MIRS) was developed to characterize soil organic matter (SOM) chemistry in soils. The pyrolyzer was interfaced to the MIR spectrometer by means of a Brill cell™ (CDS Analytica). The set-up generates pyrolysis fingerprint spectra from which individual pyrolysis products can be related to SOM bulk chemistry. Py-MIRS development involved the testing of experimental conditions like pyrolysis temperature (550, 700, 1000 °C), heating rate (20 °C s−1 and 20 °C ms−1) and time (15, 30 and 60 s) using reference standard compounds ranging from carbohydrates to phenols varying in chemical and structural composition like levoglusogan, gluten, tannin, syringol, pectin and leucine falling within different compound categories (carbohydrates, amino acids, proteins, phenols, etc) as well as soil samples. Pyrolysis yields of prominent specific functional groups, like aliphatics (C-H stretching at 2930 cm−1) and Cdouble bond; length as m-dashC aromatics (1510 cm−1), varied with pyrolysis temperature, heating rate and time. The preferred settings for high pyrolysis yield and minimized secondary reactions were obtained at a pyrolysis temperature of 700 °C, heating rate of 20 °C ms−1 and heating time of 30 s. The suitability of Py-MIRS to detect changes in SOM composition was evaluated by comparing Py-MIRS results to Diffuse Reflectance Fourier Transform mid-Infrared Spectroscopy (DRIFTS) results. Soil samples taken from the Static Fertilization Experiment, Bad Lauchstädt, Germany (Chernozem) revealed a major SOM contribution of the peak at 1750 cm−1 (Cdouble bond; length as m-dashO), followed by peaks at 950 (C-H), 1510 (Cdouble bond; length as m-dashC), 1176 (C-H, O-H) cm−1, with smaller contributions from the 2930 (C-H) and 3015 (CH4) cm−1 peaks, apart from a dominant CO2 peak. Using the preferred pyrolysis settings, Py-MIRS as well as DRIFTS results further indicated that soils receiving organic (e.g. farmyard manure) inputs were highly enriched in aliphatic groups, while their absence favored the accumulation of carboxyl and aromatic groups as well as polysaccharides. Py-MIRS allowed via semi-quantification of pyrolysis products a rapid monitoring of SOM bulk chemistry with a high degree of reproducibility. It was concluded that Py-MIRS represents a fast, effective and reproducible technique to characterize changes in the SOM bulk chemistry as a result of management practices. It also allows to minimize acknowledged constraints of other analytical techniques used to characterize SOM bulk chemistry such as mineral interferences and associated secondary reactions.

Dates and versions

hal-01766699 , version 1 (13-04-2018)



Nkwain Y. Funkuin, Michael S. Demyan, Frank Rasche, Marie-France Dignac, Elke Schulz, et al.. Coupling pyrolysis with mid-infrared spectroscopy (Py-MIRS) to fingerprint soil organic matter bulk chemistry. Journal of Analytical and Applied Pyrolysis, 2018, 133, ⟨10.1016/j.jaap.2018.04.004⟩. ⟨hal-01766699⟩
51 View
0 Download



Gmail Facebook X LinkedIn More