Investigations of coals by on-line coupled laser desorption/gas chromatography/mass spectrometry (LD/GC/MS)

An on-line analytical method has been developed to characterise brown coal samples and pieces from brown-coal based briquettes. The direct laser desor ption from the sample into the gas flow of a gas chromatograph/mass spectro meter (GC/MS) allows an on-line analysis of polymer or macromolecular matri ces, e.g. brown coal samples. This technique allows for analysis of coal wi thout time-wasting clean-up steps as required in a classical 'solvent-based ' analysis. In this study two brown coal samples of different origin were i nvestigated by on-line coupled laser desorption GC/MS (LD/GC/MS). The resul ts were compared with classical analytical techniques like solvent-extracti on or thermodesorption. Even though the laser pyrolysis led to distinctly d ifferent results in comparison to the classic methods, the chromatograms pr oduced were reproducible and unique for each coal. The laser desorbed produ cts can be divided into two types: pyrolysis compounds liberated from the c oal matrix and unsaturated hydrocarbons generated by laser radiation. (C) 2 000 Elsevier Science B.V. All rights reserved.