Studies of laser desorption and detection from liquid and polymeric matrices using multiphoton ionization in supersonic jet/mass spectrometry.

摘要

his work explores the desorption and highly selective analysis of thermally labile compounds and analytes in complex matrices such as liquids and polymers. Specifically, laser desorption (LD) has been used to introduce intact neutral molecules into the gas phase for detection via Resonance Enhanced Multiphoton Ionization (REMPI). The REMPI products were monitored by a reflectron time-of-flight mass spectrometer detector. Since REMPI is a highly selective technique, the resulting mass spectra contained only peaks from the analyte with no chemical noise from the liquid or polymer matrix or from the background.;Three particular areas were studied by these methods: (1) the analysis of substituted nitrobenzenes and explosive analogs was performed. The results were compared to the Atmospheric Pressure Ionization Mass Spectrometry of these compounds; (2) the analysis of aromatic polymers was also performed. It was shown that LD-REMPI-MS is useful for characterizing the monomer unit. Ions representing the molecular weight distribution of the polymers were observed only for very small polymers (MW