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MS: Massenspektrometrie

MS 4: Laser Mass Spectrometry of Molecules and Aerosols

MS 4.1: Vortrag

Dienstag, 3. April 2001, 17:15–17:30, EB 202

Laser mass spectrometry of laser desorbed organic substances using ultrashort light pulses — •Christian Weickhardt and Karen Tönnies — Lehrstuhl Physikalische Chemie und Analytik, Brandenburgische Technische Universität, Erich-Weinert-Str. 1, 03044 Cottbus

The mass spectrometric analysis of organic compounds in solids, as e.g. in soil samples, requires the transfer of the sample molecules into the gas phase. Simple thermal evaporation in many cases leads to intense destruction of the sample before a sufficient vapor pressure is achieved. In this context laser desorption is an advantageous alternative as it allows the fast and gentle evaporation of even very labile substances.
For the fast trace analysis in complex mixtures the coupling of resonant multiphoton ionization and time-of-flight mass spectrometry has proven to be a powerful tool. Its combination with laser desorption results in a fast technique for the selective trace analysis in solids which requires only a minimum of sample preparation.
In our experiments on soil samples the fourth harmonic of a pulsed Nd:YAG laser is used for desorption while photo ionization is carried out by the second or fourth harmonic of a femtosecond laser system. Several ion source designs were investigated as well as the influence of different soil types on the detection of polycyclic aromatic hydrocarbons, explosives and chemical warfare agents. Quantification was performed by internal standards and delivered satisfactory results over five orders of magnitude.