Effects of some mineral matrices on flash pyrolysis-GC of soil humic substances

The whole soil samples and the humic and fulvic acids extracted from an acid soil (Typic Dystrochrept) were mixed with calcium carbonate,calcium sulfate, silica, alumina, iron-oxide, and then subjected to pyrolysis-gas chromatography. The relative area of the 41 peaks of each pyrogram was compared and numerical parameters were used to analyse the influence of the mineral components on the pyrolytic decomposition. Calcium salts have very little or non-significant effects on soil pyrograms. Amorphous silica, alumina and iron-oxide greatly change the pyrogram pattern. The most evident effect consists of a reduction of the more polar and/or high retention time components.