Characterization of lake-aquatic humic matter isolated with two different sorbing solid techniques: pyrolysis electron impact mass spectrometry

The thermal degradation of different kinds of aquatic humic-matter fractions by means of pyrolysis (Py) in combination with mass spectrometric (MS) analyses using low energy (14 eV) electron impact (EI) ionization is reported. According to the data obtained it is difficult to divide aquatic organic solutes into real humic and non-humic matters based solely on qualitatively examination of thermal degradation products. On the contrary, the quantities of thermal degradation products were strongly correlated with the various humic-matter fractions isolated/fractionated by means of different operations. The close similarities between the principal building blocks of various organic solute-fractions isolated indicates that the formation of aquatic humic solutes based on certain universal one-way precursor-product relationship is an oversimplification of a complex process. Accordingly, isolation/fractionation procedures being purely connected with strongly acidic treatments are somewhat man-made for modelling aquatic acidic humic solutes. (C) 1999 Elsevier Science B.V. All rights reserved.