Microscale determination of inorganic nitrogen in water and soil extracts

G. K. Sims, T. R. Ellsworth, R. L. Mulvaney

Research output: Contribution to journalArticlepeer-review


Rapid, sensitive analysis of NH4N03and N02in 1–150 ul of soil extract or water was achieved using a modified indophenol blue technique adapted to microtiter plate format. The microplate technique was similar to conventional steam distillation in accuracy and precision. By varying aliquot volume, a wide linear dynamic range (0.05 to 1000 mg of NH4 +- or N03’-N L’1) was achieved without the need for sample dilution or concentration. High sample throughput (250–500 NH4 +analyses d’1) was accomplished manually, but could be significantly increased by automation. Of considerable importance was the very low waste stream produced by the method. All equipment and supplies required are commercially available and need no modifications for this use. The microtiter plate format could be used for other soil colorimetric analyses with little or no down time for equipment setup, a major consideration for commercial soil-testing laboratories. The method and equipment used are well suited to quality control and quality assurance programs, as required under FlFRA Good Laboratory Practices.

Original languageEnglish (US)
Pages (from-to)303-316
Number of pages14
JournalCommunications in Soil Science and Plant Analysis
Issue number1-2
StatePublished - Jan 1 1995

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Soil Science


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