1999, Volume 33, Pages 3469-3472 Sridhar Susarla,* T. W. Collette, A. W. Garrison, N. L. Wolfe, and S. C. McCutcheon: Perchlorate Identification in Fertilizers Six values were incorrectly reported in Table 1 (Perchlorate Concentrations in Fertilizer Components). These values, unlike those of Table 2 (Perchlorate Concentrations in Commercial Fertilizers), were based solely on ion chromatography (IC) using a Dionex AS-11 column. The corrected values below were obtained using an AS-16 column designed specifically for perchlorate analysis and were confirmed by use of perchlorate spikes. Capillary electrophoresis, with a provisional detection limit of 0.01%, did not detect perchlorate in any of the six samples.
TABLE 1. Corrections component
perchlorate (%)
phosphate rock (Western) phosphate rock (Florida) potash (commercial) potash (muriate) ammonium dihydrogen phosphate urea
NDa ND 0.004b ND ND ND
a ND, not detected by IC above 0.003%. b Potash (commercial) was confirmed by 35Cl nuclear magnetic resonance (NMR) spectroscopy.
The Table 1 values for liquid extracts from langbeinite ore and Chilean nitrate were confirmed by capillary electrophoresis and Raman spectroscopy and by other laborabories in an ongoing round-robin. TRC of Irvine, CA, prepared the extracts under the direction of the aerospace industry Perchlorate Study Group. Subsequent analysis of processed langbeinite in a solid form provided by IMC Global of Mulberry, FL, showed nondetectable levels of perchlorate. Clearly, sampling and extraction methods need to be standardized to support highly quantitative analyses of these heterogenous solid materials. For interpretation of the results from Table 2, Bill Hall (Director, Product Stewardship, IMC Global, written communcation, 7/27/99) points out that only Lesco (17-3-11) uses sulfate of potash magnesium that may be derived from langbeinite ore. The other fertilizers beside the ammonium nitrate and the Pennington product are most likely based on muriate of potash (KCl) or potassium nitrate and not langbeinite. None of the nine fertilizers is expected to contain Chilean nitrate. In Table 2, Florida licensee numbers are incorrectly reported as lot numbers, and the 7th listed product, Vigoro
224
9
ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 34, NO. 1, 2000
10-10-10, was not manufactured by Gro-Tec, but by IMC Vigoro, P.O. Box 512, Winter Haven, FL. We have recently purchased and analyzed 17 additional commercial fertilizer mixtures during the period of AugustSeptember 1999, primarily in the Athens, GA, area. Many of these mixtures are the same products reported in Table 2. Only one product contains perchlorate, based on IC using an AS-16 column. This value is about 2 orders of magnitude less than Table 2 values and just below the provisional detection limit for Raman spectroscopy, which reported non-detects for all 17, suggesting that the occurrence of perchlorate is sporadic and not as pervasive as our original data implied. Also, Bill Hall (from a survey of manufacturers, personal communcation, 10/20/99, Athens, GA) notes that the majority of the fertilizers in Table 2 are essentially lawn and garden formulations that represent less than 3-4% of the fertilizer marketed in the United States. The additional data and information on the use of the fertilizers in Table 2 indicate that our preliminary calculation of potential loading of perchlorate must not be extrapolated at this time using total consumption of nitrogen-based fertilizer tonnages in the United States. Such extrapolations require a rigorous statistical sampling of fertilizer source materials used by the large commercial sectors of the United States. Until these data are available, our estimate of 0.91 kg/ha of potential perchlorate loading should be applied consistent with the use of lawn and garden products having 0.2% perchlorate by weight. The Fertilizer Institute (Gary D. Myers, president, letter to Sridhar Susarla, 8/19/99) also notes that they are not aware of any information suggesting that coating oils are a source of perchlorate. We were premature in discussing coating oils and brines after discussions with them in March 1999. The assistance of Jackson Ellington and John Evans of this laboratory in analysis of samples by the AS-16 method is appreciated. Qunicy Teng of the University of Georgia provided results by NMR. The comments by Wayne Robarge of North Carolina State University and Bill Hall of IMC Global aided us in understanding typical agricultural use and manufacture of fertilizers, but we remain responsible for any misinterpretation in the original communication. We regret any inconvenience to the readers or to the suppliers of these samples. Mention of tradenames or commercial products does not constitute endorsement or recommendation for use by the U.S. EPA. ES992029C 10.1021/es992029c Published on Web 12/03/1999
