Environmental trace analysis by ion trap mass spectrometry
- Los Alamos National Lab., NM (United States)
The ion trap mass spectrometer has many qualities that make it especially attractive for field environmental trace analysis. The most obvious is its demonstrated high sensitivity. The ion trap is also tolerant of high pressures; is adaptable to a variety of inlet and sampling systems; has mechanical and electrical simplicity; and can operate in an AC-only mode. We have applied the ion trap to a variety of problems in environmental analysis, which will be mentioned briefly. However, this presentation will focus on selective sampling methods for laser desorption ion trap mass spectrometry. Selective sampling methods have many advantages including the reduction of chemical noise; improved sensitivity; and, perhaps most importantly, circumvention of some of the well-known problems caused by space-charge effects. These methods include selective sorbents that both collect sample and serve as the platform for desorption ionization and resonant laser ablation to selectively ionize ablated materials for elemental analysis. Selective sorbents include zeolites and modified silica fibers. These materials provide a fast, simple, and inexpensive means to sample contaminants directly from the environmental matrix, through simple chemical modification of their surfaces, collection efficiencies can be enhanced. Resonant laser ablation is a multistep process to evaporate and subsequently ionize elemental species in a solid sample. The leading edge of a tunable laser pulse vaporizes near-surface material, while the trailing edge of the pulse resonantly excites, and subsequently ionizes, the component of interest. Preliminary data suggest that attogram detectabilities can be achieved in this fashion.
- OSTI ID:
- 466544
- Report Number(s):
- CONF-951017--
- Country of Publication:
- United States
- Language:
- English
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