Schneider, E.; Levsen, K. Fresenius 2. Anal. Chem. 1987, 326, 43-48. Simms, J. R.; Keough, K.; Ward, S. R.; Moore, B. L.; Bandurraga, M. M. Anal. Chem. 1988, 60, 2613-2620. Wernery, J. D.; Peake, D. A. Rapid Commun. Mass SDectrom. 1989. 3. 396-399. Barber, L. B., Jr. Ground Water 1988,26, 696-702. LeBlanc, D. R. U S . Geol. Surv. Water-SupplyPap. 1984, No. 2218. LeBlanc, D. R.; Garabedian, S. P.; Quadri, R. D.; Morin, R. H.; Teasdale, W. E.; Paillet, F. L. Open File Rep.-US. Geol. Surv. 1987, No. 86-481. Techniques of Water Resources Investigations; Wershaw, R. L., Fishman, M. J., Grabbe, R. R., Lowe, L. E., Eds.; US. Geological Survey: Reston, VA, 1983; Book 5, Chapter A3. USEPA Method 200.7. USEPA Methods f o r Analysis of Water and Wastes; U.S. Government Printing Office: Washington, DC, 1983. Barber, L. B., 11; Thurman, E. M.; Schroeder, M. P.; Leblanc. D. R. Environ. Sci. Technol. 1988. 22, 205-211. Hand, V. C.; Williams, G. K. Environ. Sci: Technol. 1987, 21, 370-373. Schoberl, P. Tenside, Surfactants, Deterg. 1989,26,86-94. Kimerle, R. A.; Swisher, R. S. Water Res. 1977,11,31-37.
Borgerding, A. J.; Hites, R. A. Submitted for publication in Anal. Chem. Drozd, J. C.; Gorman, W. J. Am. Oil Chem. soc. 19h8,65, 398-404. Moreno, A.; Bravo, J.; Berna, J. L. J. Am. Oil Chenz. Soc. 1988,65, 1000-1006. Field, J. A. Ph.D. Thesis, Colorado School of Mines. 1990, Larson, R. J. In The Biotransformation and Fate of Chemicals in the Aquatic Environment. Proceedinrs of a workshop held at the Univ. of Michigan Biological Station, Pellston, MI, Aug 14-18, 1979; pp 63-85. Halvorsan, H.; Ishaque, M. Can. J. Microbial. 19F9, 15, 571-576. Wagener, S.; Schink, B. Water Res. 1987, 21, 61*-4?2. Kimerle, R. A.; Swisher, R. D. Water Res. 1977,11, 31-37. Brown, V. M.; Abram, F. S. H.; Collins, L. J. Tenside Ijeterg. 1978, 15, 57-59. Abel, P. D. J. Fish Biol. 1974, 6, 279-298. Larson, R. J. Enuiron. Sci. Technol. 1990,24, 1241-1246.
Received for review July 10, 1991. Revised manuscript rweiued January 8,1992. Accepted January 16,1992. The use of brand names in this report is for identification purposes only and does not imply endorsement by the U.S. Geological Survey.
Reaction of Suwannee River Fulvic Acid with Chloramine: Characterization of Products via 15N NMR Arwa S. Glnwalla and Mlchael A. Mlklta”
Chemistry Department, California State University, Bakersfield, California 93311 ~~~~~
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rn Suwannee River fulvic acid was reacted with aqueous solutions of 15N-labeledchloramine and 15N-labeledammonia. INEPT 15N-NMR spectra of the lyophilized products from both reactions exhibit major resonances between 90 and 120 ppm, denoting the formation of amides, enaminones, and/or aminoquinones. The striking similarity between spectra suggests that the observed N moieties result from reactions between fulvic acid and ammonia, an expected coproduct from the chlorination of the fulvic acid by Chloramine. This represents the first evidence for the formation of N-containing compounds from the chloramination of dissolved organic matter in natural waters. Introduction A link between humic substances and public health first became apparent in 1974, with the report by Rook demonstrating that humic substances are precursors to toxic haloforms during the chlorination of municipal water supplies ( I ) . Since then, a variety of alternative aqueous disinfectants have been examined. Chloramine (NH2C1) has received considerable attention since it was demonstrated that the addition of ammonia to conventional chlorination dramatically reduced haloform production (2). Before chloramine can be considered a significant improvement to chlorine, however, its complete reaction chemistry with dissolved organic matter must first be delineated. Two groups have been particularly active in examining the chlorination of humic substances by chloramine. Via gas chromatography/mass spectrometry (GC/MS), Johnson and colleagues have examined ethersoluble fractions from the reaction of Black Lake fulvic acid with chloramine (3). Scully and co-workers have identified organic N-chloramines during the chloramination of modified primary effluent and selected amino 1148 Environ. Scl. Technol., Vol. 26, No. 6, 1992
acids (4). They have also considered the possible toxicological significance of chloramines in drinking water through the reaction of simple models of biomolecules and a review of the literature (5). While such studies have significantly enhanced the understanding as to how chlorine is incorporated into humic substances upon reaction with chloramine, none has elucidated whether nitrogen moieties are formed. We have recently demonstrated that the combination of NMR-active isotopically-enriched reagents and NMR analyses is a powerful technique for examining tke reactions of humic materials (6);i.e., it is nondestructive and permits analyses of the whole sample. Such a method complements GC/MS analyses that examine ether-duble fractions which represent only a small percentage of the starting humic substance. Following the reactions of hwlc substances directly is also an improvement over Ehe use of model compounds, since no single model or group of models adequately reflects the structure of humic substances. In a series of reports, we have initiated the use 15h’ NMR to study the reaction chemistry of humic substances with 15N-labeledreagents. For example, we have shown that hydroxylamine reacts with quinones in humic substances to form monooximes (7). This paper describes theaPplication of this method to the reaction of Suwanne. River fulvic acid with 15N-labeledchloramine. We selected SUwannee River fulvic acid for analysis because it is the most structurally understood humic substance and a commer‘ cially available International Humic Substances Society (IHSS) “standard”. Experimental Section Suwannee River fulvic acid was obtained from J. A* Leenheer, USGS National Water Quality Labcgratory, Arvada, CO. Elemental analyses were performed, l t least
0013-936X/92/0926-1148$03.00/0
0 1992 American Chemicsi Sociew
in duplicate, by Huffman Laboratories, Inc., Golden, CO, are reported as averages with observed ranges. Chloramine Reaction. Aqueous chloramine was prepared as modified from Johnson and Overby (8) by the simultaneous addition of 115 mL of 2.0 mM sodium hypochlorite (Chlorox) and 115 mL of 2.0 mM labeled ammonium chloride (15N,99%; Cambridge Isotope Laboratories), The addition rate of the ammonium chloride solution was maintained at twice that of the sodium hypochlorite. The resulting solution had a pH of 6.6 and was raised to a pH of 11.2 using 50% sodium hydroxide. The identification of chloramine was confirmed by its characteristic UV absorption maximum at 243 nm as measured on a Beckman DU-7 UV-vis spectrometer. This solution ~ 8 found 9 to be approximately 1mM in chloramine using Beer’s law and its published molar absorptivity of 416 (9). This chloramine solution was cooled to 0 OC, and 150 mg of Suwannee River fulvic acid dissolved in 7.5 mL of 0.01 M sodium hydroxide, which had 1 added drop of 50% sodium hydroxide. The resulting amber solution had a pH of 10.5, was allowed to warm to room temperature, and then was stirred for 5 days. This solution was then passed through acidified cation ion-exchange resin (Baker C-350) and then lyophilized to yield 120 mg of yellowish-brown material (80% recovery). A “chloramine blank“ was performed to ensure that the observed resonances were indeed attributable to reactions between chloramine and fulvic acid, and not some artifact of the experimental procedure (e.g., reaction between residual chloramine and the ion-exchange resin). To this end, the above procedure was repeated without the addition of fulvic acid. No visible or measurable (i.e.,
