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This article in JEQ

  1. Vol. 29 No. 6, p. 1890-1895
    Received: Sept 20, 1999

    * Corresponding author(s): mulvaney@uiuc.edu
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Evaluation of Diffusion for Inorganic-Nitrogen Analysis of Natural Water and Wastewater

  1. S. A. Khan,
  2. R. L. Mulvaney *,
  3. K. Strle and
  4. B. P. Horgan
  1. Department of Natural Resources and Environmental Sciences, Univ. of Illinois, 1102 S. Goodwin Ave., Urbana, IL 61801.



Public concern that agricultural use of N fertilizers may have adverse effects on environmental quality and human health has led to a growing need for reliable data concerning the concentration of inorganic N in ground and surface water. A study was conducted to compare the accuracy and precision of simple Mason-jar diffusion methods for quantitative determination of NH+4 and NO3, in a wide variety of water and wastewater, relative to colorimetry, ion-selective potentiometry, and steam distillation. Good agreement among methods was generally obtained with standard solutions prepared using deionized water; however, substantial differences often were observed with natural and anthropogenic samples, because of either Cl interference in measurements with the NO3 electrode or CO2−3 interference in distillation. Analytical accuracy also was evaluated by measuring recovery of N added as (NH4)2SO4 or KNO3, (6 mg N L−1). With most of the samples studied, quantitative recovery (97–103%) was not achieved by potentiometry or distillation. Quantitative recoveries usually were achieved by a manual Berthelot method for colorimetric determination of NH+4, whereas recovery was often incomplete when NO3 analyses were performed with an automated flow-injection system using Cd2+ reduction. Regardless of the sample matrix, diffusion was always accurate in measuring recovery of NH+4 or NO3.

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