Time-resolved pyrolysis field ionization mass spectrometry of humic material isolated from freshwater

Journal Article · Wed Apr 01 04:00:00 EST 1987 · Environ. Sci. Technol.; (United States)

DOI:https://doi.org/10.1021/es00158a003· OSTI ID:6705534

Schulten, H R; Abbt-Braun, G; Frimmel, F H

The thermal degradation of aquatic humics in combination with mass spectrometric analyses using field ionization (FI) as a soft ionization method is reported. Since FI mass spectra of the pyrolysis (Py) products consist almost exclusively of molecular ions and mass spectrometric fragmentation even of relatively polar substances is strongly reduced, the characterization of biomacromolecules is facilitated and the identification of direct, primary building blocks is achieved. Furthermore, the thermal behavior of characteristic classes of humic constituents is investigated by time/temperature-resolved FI mass spectrometry (MS) with the commercially available direct-probe introduction system. A general characterization of the Py products of humics and the ratios of volatilized matter and residual char are given. These methods permit insight into the thermal degradation processes of complex polymeric biomatter. In contrast to the humic acid (HA) investigated, for fulvic acid (FA) a larger amount of pyrolysates is formed, indicating less thermal stability. The Py mass spectra of the HA and FA show monomers and higher aggregated chemical species of furan, phenol, methoxyphenol, and dimethoxyphenol subunits. Chemical reactions such as alternating methylation and oxidation steps of FA lead to characteristically different results: in the Py mass spectrum of the methylated-oxidized FA the m/z values of benzenecarboxylic acids, methoxybenzene-carboxylic acids, and monobasic aliphatic acids show high intensities, whereas methyl esters of benzenecarboxylic acids and aliphatic dibasic acids dominate in the case of the mass spectrum of the oxidized-methylated FA. 32 references, 5 figures, 4 tables.

• Research Organization: Fachhochschule Fresenius, Wiesbaden, West Germany
• OSTI ID: 6705534
• Journal Information: Environ. Sci. Technol.; (United States), Journal Name: Environ. Sci. Technol.; (United States) Vol. 21:4; ISSN ESTHA
• Country of Publication: United States
• Language: English

Related Subjects

520200* -- Environment
Aquatic-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
DATA
DECOMPOSITION
EXPERIMENTAL DATA
FRESH WATER
FULVIC ACIDS
HUMIC ACIDS
HUMUS
HYDROGEN COMPOUNDS
INFORMATION
MASS SPECTROSCOPY
METHYLATION
MOLECULAR STRUCTURE
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDATION
OXYGEN COMPOUNDS
POLLUTION
PYROLYSIS
SPECTROSCOPY
THERMOCHEMICAL PROCESSES
WATER
WATER POLLUTION