A microscale method for colorimetric determination of urea in soil extracts

N. S. Greenan, R. L. Mulvaney, G. K. Sims

Research output: Contribution to journalArticlepeer-review


The diacetyl monoxime colorimetric method of determining urea in soil extracts was modified for microplate format. A 100-μL aliquot of extract was treated with color reagent in a disposable plastic microtiter plate (96 wells/plate), and color was developed by heating the plate in a low-temperature oven at 87°C for 55 min. After cooling for 20 min at ambient temperature, absorbance measurements were simultaneously performed on all 96 wells using a microplate reader. The microscale method was faster and more convenient than the conventional method; moreover, the volume of waste was markedly reduced. Studies to compare the two methods showed very little difference in accuracy, precision, or sensitivity.

Original languageEnglish (US)
Pages (from-to)2519-2529
Number of pages11
JournalCommunications in Soil Science and Plant Analysis
Issue number15-16
StatePublished - Sep 1 1995

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Soil Science


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