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Determination of pH in human erythrocytes. Sources of systematic error

D Büttner1, J Büttner

  • 1Institut für Klinische Chemie I, Medizinische Hochschule Hannover, Germany. joh.buettner@t-online.de

Clinical Chemistry and Laboratory Medicine
|December 16, 1998
PubMed

Insights

The potentiometric and 5,5-dimethyl-2,4-oxazolidinedione (DMO) methods for measuring erythrocyte pH showed minor differences. Accounting for liquid-junction potentials reconciled the methods, indicating the DMO method is accurate for pH determination.

Area of Science:

  • Physiology
  • Biochemistry
  • Analytical Chemistry

Background:

  • Accurate intracellular pH measurement is crucial for understanding cellular function.
  • Discrepancies exist between potentiometric and tracer-based pH determination methods.

Purpose of the Study:

  • To compare the potentiometric method with the 14C-labelled 5,5-dimethyl-2,4-oxazolidinedione (DMO) method for erythrocyte pH determination.
  • To identify and correct for discrepancies between the two methods.

Main Methods:

  • Simultaneous measurement of erythrocyte pH using potentiometry and the DMO method.
  • Analysis of liquid-junction potentials in potentiometric measurements.
  • Comparison of extracellular to intracellular H+ ion concentration ratios.

Main Results:

  • A mean method difference of 0.026 pH units was observed.
  • Incorporating liquid-junction potentials into potentiometric calculations yielded consistent results with the DMO method.
  • The DMO method demonstrated no systematic errors and agreed with other ion distribution ratios.

Conclusions:

  • The DMO method is a reliable technique for accurate intracellular pH measurement in erythrocytes.
  • Liquid-junction potentials are a significant factor affecting potentiometric pH measurements in biological matrices.
  • Correcting for these potentials enhances the accuracy of potentiometric pH determination.

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