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ALTERNATIVE TECHNIQUES FOR MEASUREMENT OF PERCHLORATE IN FERTILIZER AND ENVIRONMENTAL SAMPLES
Citation:
Wolfe, N L., T W. Collette, A W. Garrison, S. Susarla, AND Q. Teng. ALTERNATIVE TECHNIQUES FOR MEASUREMENT OF PERCHLORATE IN FERTILIZER AND ENVIRONMENTAL SAMPLES. Presented at 20th Annual Society of Environmental Toxicology and Chemistry Meeting, Philadelphia, PA, November 14-18, 1999.
Description:
The Perchlorate anion has been implicated as a potentially serious environmental pollutant, being found in drinking water and irrigated crops. Commercial fertilizers have recently been shown to contain high levels of Perchlorate impurities and thus be potentially important sources of the pollutant. Ion chromatography (IC) with conductivity detection is the established technique for Perchlorate analysis in environmental samples. In investigating the occurrences of perchlorate in various fertilizers, however, it became necessary to develop techniques for confirmation of Perchlorate and, if possible, for improved routine quantitative analysis. Thus, we have investigated the applications of 3 widely varying analytical technologies to this problem: 1) capillary electrophoresis (CE), 2) Raman spectroscopy (RS), and 3) NMR spectroscopy. In each case, trial samples consisted of simple filtered aqueous extracts, diluted if necessary, of 8 solid commercial fertilizers of varying composition. CE involved a coated column to reduce the electroosmotic flow, using reversed polarity and indirect UV detection with pyromellitic acid as visualization reagent. Perchlorate, chlorate, chlorite, and chloride were separated, detected and quantified by this method. RS using 785nm diode laser excitation and a fiber optic probe coupled with a charge-coupled-device detector provided an unambiguous fingerprint for all these anions except chloride; the Perchlorate spectrum from the fertilizer solutions could be obtained directly through the glass sample vial. NMR of the 35Cl nucleus resulted in a single sharp peak specific for the Perchlorate species. Using each of these techniques, the presence of the Perchlorate anion was confirmed in each fertilizer sample. Further research is underway to determine detection limits and other analytical parameters for each of the techniques when applied to the measurement of anionic chlorine species in various fertilizers.