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This article in SSSAJ

  1. Vol. 51 No. 1, p. 72-74
    Received: May 19, 1986

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Single Column Ion Chromatography: III. Determination of Orthophosphate in Soils1

  1. U. Karlson and
  2. W. T. Frankenberger2



A chromatographic procedure was developed to determine orthophosphate in aqueous soil extracts by single column ion chromatography (SCIC) with conductimetric detection. The eluent stream consisted of 1.5 mM phthalic acid adjusted to pH 2.7 with formic acid. The method allows precise (RSD = 1.1-3.3%) measurements of trace amounts of orthophosphate (detection limit = 0.3 µg L−1) in the presence of high background levels of Cl- and NO-3. Analysis of orthophosphate by SCIC closely agrees to those values obtained with an AutoAnalyzer based on the Mo blue chromophore reaction. Under the chromatographic conditions described, elution of orthophosphate occurred at 6 min while Cl- and NO-3 had respective retention times of 11 and 20 min. Single column ion chromatography proves to be a rapid and routine method for determination of orthophosphate with greater sensitivity than the conventional colorimetric methods.

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