Improved apparatus for the differential measurement of pH: Applications to the measurement of glucose

Andrea Mosca, Guilio Dossi, Massimo Luzzana, Luigi Rossi Bernardi, Walter S. Friauf, Robert L. Berger, Harry P. Hopkins, Virginia Carey

Research output: Contribution to journalArticlepeer-review


Two improved systems for the determination of the difference in pH between two solutions at the same temperature are described, both of which have a long-term stability of ±1 × 10-4 pH unit and a peak-to-peak noise level of 5 × 10-5 pH unit when operated in the differential mode. The cells are constructed of Delrin which has been found to be inert in biological fluids. These cells, with a volume of 1 ml, can be electrically connected to each other via a dialysis membrane and are thermostated during the duration of the pH measurements to ±0.01°C. In a second configuration, combination microelectrodes are inserted into each cell; thus the dialysis membrane is not necessary. To demonstrate the application of these systems to reactions of biological interest where pH changes occur, we investigated the hexokinase-catalyzed reaction between ATP and glucose in a phosphate buffer. The concentrations of glucose determined from the observed changes in pH by a numerical solution to the equilibrium equations are in excellent agreement with the analytical values.

Original languageEnglish
Pages (from-to)287-294
Number of pages8
JournalAnalytical Biochemistry
Issue number2
Publication statusPublished - 1981

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology


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