Important progress has been made, with the help of NIEHS, toward effectively utilizing microwave induced plasma atomic emission spectrometry (MIP), as a means of detecting and quantifying chlorodioxin and other types of halocarbon samples such as insecticides. Particularly important to this progress has been the design and implementation of low flow torches (LFT; torches are plasma containment devices) which add enhanced stability and precision to the plasma detector. These torches have been initially characterized for their analytical figures of merit such as detection limit, linear response range, etc. This evidence suggests the analytical performance should be better than with previous studies involving the plasmas as GC detectors. It also suggests that suprathermal ionization (ionization in excess of that predicted by theoretical calculations) will be the normal course in operating the plasmas contained in the LFTs. As indicated in the text, the best detection levels for halocarbons such as dioxins or other organic compounds are in tenths-of-nanogram range, absolute, by GC-MIP or GC-mass spectrometry. Both of these methods allow selectivity and if operated in the appropriate mode lead to empirical formulae as well as quantitative trace analysis. To date having these valuable advantages has meant tradeoff of the sensitivity afforded by certain group sensitive detectors such as electron capture which is a factor of 10 or lower in detectability. GC-MIP can be an attractive alternative to GC-MS. A new approach which shows great promise is to utilize the ionizing capabilities of the plasma instead of its optical emission qualities. The limitations with optical emission come from the difficulty in enhancing signal/noise--S/N or signal to background--S/B, because at increased plasma power levels the optical background becomes more pronounced than the signal. If, however, we can successfully couple the MIP as an ion source to MS, and extract the ions efficiently, then detection levels should drop by a factor of 10-100, while preserving the important elemental analysis capabilities. This proposal then extends the previous work by markedly altering the plasma experiment as well as the usual GC-MS experiment to take advantage of the unique qualities of both. The plasma-MS experiments for metals with solution nebulization show one or two order of magnitude improvements easily. With non-metals the same or better should be possible. After all, the GC in effect removes most of the interfering matrix whereas solution nebulization does not.
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