Skip to main content
ARS Home » Research » Publications at this Location » Publication #293698
Title: Progressing towards more quantitative analytical pyrolysis of soil organic matter using molecular beam mass spectroscopy of whole soils and added standards

Author
item HADDIX, M - COLORADO STATE UNIVERSITY
item CALDERON, FRANCISCO
item CONANT, R - COLORADO STATE UNIVERSITY
item MAGRINI-BAIR, K - DEPARTMENT OF ENERGY
item PAUL, E - COLORADO STATE UNIVERSITY
item EVANS, R - MICROCHEM TECHNOLOGIES INC.
item WALLENSTEIN, M - COLORADO STATE UNIVERSITY
item MORRIS, S - BRADLEY UNIVERSITY

Submitted to: Geoderma
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/28/2016
Publication Date: 9/16/2016
Publication URL: http://handle.nal.usda.gov/10113/5643586
Citation: Haddix, M., Calderon, F.J., Conant, R., Magrini-Bair, K., Paul, E.A., Evans, R., Wallenstein, M.D., Morris, S.J. 2016. Progressing towards more quantitative analytical pyrolysis of soil organic matter using molecular beam mass spectroscopy of whole soils and added standards. Geoderma. 283(1):88-100. doi:10.1016/j.geoderma.2016.07.027.

Interpretive Summary: In this experiment, we added different organic substances to soil in order to test the sensitivity of analytical pyrolysis mass spectrometry to changes in soil carbon chemistry. This will be very useful knowledge because analytical pyrolysis mass spectrometry can be an inexpensive and rapid way to analyze soil organic matter and test the effect of farming practices or environmental disturbances on soil quality.

Technical Abstract: Soil organic matter (SOM) is extremely complex and composed of hundreds of different soil organic C (SOC) compounds. It has been difficult to establish quantitative methods that identify meaningful fractions from a dynamics-ecosystem functioning standpoint. Analytical pyrolysis has been used to compare chemical differences between soils, but its ability to measure the absolute amount of a particular compound in the soil is still in question. Our objective in this study was to determine if it is possible to make this method more quantitative, utilizing pyrolysis-molecular beam mass spectrometry (py-MBMS) by determining the signature of known standards and biological samples. We found an average relationship of r2=0.78 for the amount of cellulose added and the ion intensity of select m/z characteristic of the compound. There was an improved r2 of 0.94 for the amount of indole added and the ion intensity of the associated mass variables (mass/charge). Determination of the spectra of pure compounds relative to the spectra of the compounds added to soil and clay indicate that there is some interference dependent on the soils and compounds utilized. The three different soils utilized in this study had similar amounts of C pyrolyzed (54-57%). Mid infra red spectrometric analyses of the material remaining after pyrolysis showed that pyrolysis resulted in reductions in the 3400, 2930-2870, 1660 and 1430 cm-1regions primarily representative of O-H and N-H bonds, aliphatic CH, amides, and polysaccharides. The incorporation of standards into routine analytical pyrolysis provides more quantitative results and more opportunities for this method.