A transportable turnkey gas chromatograph/ion trap detector for field analysis of environmental samples

We have developed two transportable gas chromatograph/ion trap detectors (GC/ITD) for the in-situ characterization of chemical waste sites. These instruments are based on a modular design and can be readily modified in the field for air, water, or soil sampling. A purge-and-trap GC is used for the separation of volatile organic compounds before their introduction to the ion trap for mass spectral analysis. A secondary, or daughter, microprocessor controls ancillary hardware by means of the ion trap software. Most analyses are accomplished in an automated 20-min procedure. The detection limit for trichloroethylene in water is in the low part-per-trillion range. The analysis of soil and water samples is demonstrated by using surrogate samples spiked with 24 volatile organic compounds. The first instrument has been used under field conditions for soil analysis at a chemical waste site. The second-generation instrument differs from the first in the extensive use of commercially available equipment. The second-generation instrument will be briefly described here and some preliminary comparisons will be made to the first instrument. 11 refs., 8 figs., 2 tabs

Laser desorption in an ion trap mass spectrometer

Laser desorption in a ion-trap mass spectrometer shows significant promise for both qualitative and trace analysis. Several aspects of this methodology are discussed in this work. We previously demonstrated the generation of both negative and positive ions by laser desorption directly within a quadrupole ion trap. In the present work, we explore various combinations of d.c., r.f., and time-varying fields in order to optimize laser generated signals. In addition, we report on the application of this method to analyze samples containing compounds such as amines, metal complexes, carbon clusters, and polynuclear aromatic hydrocarbons. In some cases the ability to rapidly switch between positive and negative ion modes provides sufficient specificity to distinguish different compounds of a mixture with a single stage of mass spectrometry. In other experiments, we combined intensity variation studies with tandem mass spectrometry experiments and positive and negative ion detection to further enhance specificity

Laser desorption in an ion-trap mass spectrometer

Laser desorption in a ion-trap mass spectrometer shows significant promise for both qualitative and trace analysis. Several aspects of this methodology are discussed in this work. We previously demonstrated the generation of both negative and positive ions by laser desorption directly within a quadrupole ion trap. In the present work, we explore various combinations of d.c., r.f., and time-varying fields in order to optimize laser generated signals. In addition, we report on the application of this method to analyze samples containing compounds such as amines, metal complexes, carbon clusters, and polynuclear aromatic hydrocarbons. In some cases the ability to rapidly switch between positive and negative ion modes provides sufficient specificity to distinguish different compounds of a mixture with a single stage of mass spectrometry. In other experiments, we combined intensity variation studies with tandem mass spectrometry experiments and positive and negative ion detection to further enhance specificity