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PULSED SPLITLESS AND LARGE-VOLUME INJECTION IN CAPILLARY GAS CHROMATOGRAPHY MASS SPECTROMETRY FOR THE DETERMINATION OF ULTRA-TRACE LEVEL PESTICIDE RESIDUES
Citation:
Rosal, C G., L A. Riddick, G M. Momplaisir, E M. Heithmar, AND K E. Varner. PULSED SPLITLESS AND LARGE-VOLUME INJECTION IN CAPILLARY GAS CHROMATOGRAPHY MASS SPECTROMETRY FOR THE DETERMINATION OF ULTRA-TRACE LEVEL PESTICIDE RESIDUES. Presented at National Environmental Monitoring Conference 2003, Arlington, VA, July 21-24, 2003.
Impact/Purpose:
The overall goals of the task are to apply NERL's core capability in advanced chemical science and technology for maximum benefit in estimating exposures of ecosystems and humans to chemical stressors and to identify emerging pollution concerns, in particular long-range airborne transport of contaminants. This task comprises several subtasks, each with individual objectives:
Subtask 1: screen exposures of National Park PRIMENet ecosystems to chemical stressors, identifying indications of exposure requiring further evaluation, and use these samples evaluate new analytical methods as replacements for standard methods in future assessments of ecosystem contaminant exposures.
Subtask 2: evaluate a new mercury analytical approach with superior performance on complex solid matrices such as biological tissues, and apply the approach to estimating exposure of ecosystems and humans to mercury.
Subtask 3: determine distribution patterns of chemical contaminants in the southern Sierra Nevada Range of California, investigate topographic and weather factors that may influence the distributions, and determine if a correlation exists between contaminant distributions and extirpation patterns of the mountain yellow-legged frog.
Subtask 4: provide analytical methods to measure a number of inorganic and organic arsenic species in a variety of environmental matrices, elucidate the environmental transformations undergone by organoarsenic animal-feed additives, and determine if the potential exists for substantially increased exposure of humans and aquatic organisms to arsenic.
Description:
The possible presence of ultra-trace levels (sub- parts per trillion) of pesticides in pristine aquatic environments (e.g., alpine lakes) would raise questions regarding potential effects on biota. One hypothesis is that agricultural pesticides that are heavily applied in the San Joaquin Valley , California have drifted to the east of the valley, have been deposited along wind paths, and have reached high-elevation lakes of the Sierra Nevada. If so, these pesticides could be responsible for the disappearance of the mountain yellow-legged frogs. Conventional analytical techniques using gas chromatography/mass spectrometry (GC/MS) for the determination of these pollutants cannot detect sub-parts per trillion levels. In order to quantify ultra-trace levels of pesticides, it is necessary to develop an analytical method for accurate and reliable determination of these pollutants. Toward this end, this poster presents experimental results for two sample introduction techniques, pulsed splitless injection (PSI) and large-volume injection (L VI), into a capillary column GC/MS. PSI introduces 1 uL of sample into the inlet liner at a pulsed high pressure, while L VI slowly injects at least 20 uL of sample into the GC inlet liner at a temperature below the solvent's boiling point. Optimization of parameters and analytical figures of merit for the two techniques will be presented.