THE ANALYSIS OF SOIL ORGANIC-MATTER BY PYROLYSIS FIELD-IONIZATION MASS-SPECTROMETRY

At the present time, the analysis of organic matter (OM) in soils requires extraction of the OM, fractionation of the extract into humic acid (HA), fulvic acid (FA), and humin, and purification of each fraction prior to more detailed characterization by chemical, spectroscopic, and other methods. To obviate the need for these laborious and possibly damaging procedures, we examined the possibility of applying pyrolysis-field ionization mass spectrometry (Py-FIMS), a method that provides information at the molecular level on complex organic materials, to whole soils and HAs, FAs, and humins separated from these soils. In all materials, carbohydrates, phenols, lignin monomers and dimers, and, to a lesser extent, n-fatty acids were the major components. Our data indicate that whole soils are the most suitable materials for the analysis of OM in soils. Thus, Py-FIMS has all advantage compared with existing methods in that it permits soil chemists and other interested scientists to do comprehensive OM analyses on air-dry soils, even ones with low OM contents, without any pretreatment.