An improved electrode for the assay of urea in blood

G. G. Guilbault, Geza Nagy, S. S. Kuan

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44 Citations (Scopus)


An improved urea enzyme electrode is applied for the determination of urea in blood samples. The electrode is based on the enzymatic hydrolysis of urea, and potentiometric detection of the ammonium ion produced. A silicone rubber-based nonactin ammonium ion-selective electrode serves as the sensor. The selectivity coefficients of this electrode were 6.5 for NH4+/K+; 750 for NH4+/Na+, and much higher for other cations. The reaction layer of the electrode was made of urease enzyme chemically immobilized on polyacrylic gel. The prepared gel was stable at 4° for over four months. The electrodes retained their activity for over one month. A three-electrode system, which allowed dilution to a constant interference level, was applied to avoid interfering effects in blood samples. Analyses of blood sera showed good agreement with a standard spectrophotometric method. Routine clinical assays of blood urea are feasible.

Original languageEnglish
Pages (from-to)195-201
Number of pages7
JournalAnalytica Chimica Acta
Issue number1
Publication statusPublished - Nov 1973

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry
  • Environmental Chemistry
  • Spectroscopy

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