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DETERMINATION OF PERCHLORATE AT PARTS-PER-BILLION LEVELS IN PLANTS BY ION CHROMATOGRAPHY
Citation:
Ellington, J J. AND J J. Evans. DETERMINATION OF PERCHLORATE AT PARTS-PER-BILLION LEVELS IN PLANTS BY ION CHROMATOGRAPHY. Presented at 21st Annual Society of Environmental Toxicology and Chemistry Meeting, Nashville, TN, November 12-16, 2000.
Impact/Purpose:
Elucidate and model the underlying processes (physical, chemical, enzymatic, biological, and geochemical) that describe the species-specific transformation and transport of organic contaminants and nutrients in environmental and biological systems. Develop and integrate chemical behavior parameterization models (e.g., SPARC), chemical-process models, and ecosystem-characterization models into reactive-transport models.
Description:
A standardized method for the analysis of perchlorate in plants was developed, based on dry weight, and applied to the analysis of plant organs, foodstuffs, and plant products. The procedure greatly reduced the ionic interferences in water extracts of plant materials. The high background conductivity increases method detection limits with conductivity detectors. Ion chromatography (IC) on an AS 16 anion exchange column was used for separation of perchlorate from the ionic matrix. The method utilized the seemingly contradictory high water solubility but hydrophobic and unreactive character of the perchlorate anion to greatly reduce the ions in plant extracts without loss of perchlorate. The extract was heated to precipitate proteins, centrifuged, exposed to alumina, and filtered through a cartridge filled with divinylbenzene to yield a water clear extract for IC analysis, even from highly colored solutions. The quantitation limit in lettuce and tomato matrices was determined to be 250 ppb. The method will be described in detail and application to other food matrices and further research to lower the quantitation limit to 100 ppb will also be discussed.