Evaluation of the residual liquid junction potential contribution to the uncertainty in pH measurement: A case study on low ionic strength natural waters

2010 ◽  
Vol 664 (2) ◽  
pp. 129-135 ◽  
Author(s):  
Rouvim Kadis ◽  
Ivo Leito
Keyword(s):  
Ionic Strength ◽  
Natural Waters ◽  
Ph Measurement ◽  
Potential Contribution ◽  
Residual Liquid ◽  
Liquid Junction Potential ◽  
Liquid Junction ◽  
Low Ionic Strength ◽  
Junction Potential

Effects of residual liquid junction potential in direct potentiometry of potassium.

1984 ◽  
Vol 30 (3) ◽  
pp. 482-484 ◽  
Author(s):  
J W Winkelman ◽  
C Merritt ◽  
W J Scott ◽  
A Kumar ◽  
G Baum
Keyword(s):  
Ionic Strength ◽  
Residual Liquid ◽  
Small Decrease ◽  
Liquid Junction Potential ◽  
Solution Composition ◽  
Liquid Junction ◽  
Reasonable Estimate ◽  
Direct Potentiometry ◽  
Plasma Electrolyte ◽  
Junction Potential

Abstract To further the accurate direct potentiometry of plasma electrolyte concentrations, we investigated the effects of solution composition on the residual liquid junction potential (RLJP) during measurement of K+. Assuming that the binding constant between K+ and proteins or bicarbonate is no greater than with Na+, we calculate that the amount of bound K+ can be neglected. A significant RLJP exists between simple solutions containing Na+, K+, and Cl- ions and solutions containing Na+, K+, Cl-, and HCO3- ions. Replacing Cl- with HCO3- leads to an increase in the RLJP, which in turn contributes to a negative error in K+ analysis. A small decrease in RLJP is observed as the ionic strength is increased. The Henderson equation gives a reasonable estimate of the magnitude of the observed RLJP, even though the liquid junction does not meet the conditions under which the equation is rigorously applicable. Errors attributed to RLJP may be substantially minimized by using a calibrator solution that contains an anion with mobility similar to that of HCO3-.

Ion-selective electrodes for sodium and potassium: a new problem of what is measured and what should be reported.

1985 ◽  
Vol 31 (3) ◽  
pp. 482-485 ◽  
Author(s):  
A H Maas ◽  
O Siggaard-Andersen ◽  
H F Weisberg ◽  
W G Zijlstra
Keyword(s):  
Activity Coefficient ◽  
Theoretical Calculations ◽  
Pair Formation ◽  
Ion Selective Electrodes ◽  
Residual Liquid ◽  
Liquid Junction Potential ◽  
Liquid Junction ◽  
Normal Plasma ◽  
Sodium And Potassium ◽  
Junction Potential

Abstract For clinical purposes the activities of Na+ and K+ obtained with ion-selective electrodes in undiluted whole blood or serum should be multiplied by an appropriate factor to obtain the same values as the substance concentrations obtained by flame photometry. The factor is primarily dependent on the mass concentration of water in normal plasma divided by the molal activity coefficient of Na+ (or K+) of normal plasma. We discuss the value of the molal activity coefficient of Na+ obtained by theoretical calculations and by direct measurement. The discrepancies between theory and measurement (gamma Na+ of 0.747 and 0.73, respectively) may be due to some binding of Na+ (protein binding or ion pair formation), a small and variable residual liquid-junction potential, or certainty about the appropriate value for the ionic strength of normal plasma (0.16 mol/kg or somewhat higher).

Direct potentiometric measurement of sodium and potassium in whole blood.

1977 ◽  
Vol 23 (10) ◽  
pp. 1912-1916 ◽  
Author(s):  
J H Ladenson
Keyword(s):  
Whole Blood ◽  
Potassium Concentration ◽  
Residual Liquid ◽  
Liquid Junction Potential ◽  
Liquid Junction ◽  
Significant Difference ◽  
Potentiometric Measurement ◽  
Capillary Liquid ◽  
Sodium And Potassium ◽  
Junction Potential

Abstract I compared results for sodium and potassium in whole blood and plasma as measured with a newly available potentiometric analyzer, the "Orion SS-30". No significant difference was found for either sodium or potassium in 207 such comparisons. With use of the flowing, high mixing-velocity liquid junction of the Orion SS-30, the residual liquid junction potential due to blood cells was found to be less than 0.1 mV and to be independent of the hematocrit. This is in contrast to the hematocrit-dependent residual liquid junction potential of approximately 0.6 mV noted by others at normal hematocrit values with the open capillary liquid junctions now commonly used in pH instruments. I also found that the potassium concentration can increase significantly during the mixing of whole blood, and such samples should be mixed gently, if at all. Evidently sodium and potassium can be accutately and easily measured directly in heparinized blood.

scholarly journals Electrodiffusion Phenomena in Neuroscience and the Nernst–Planck–Poisson Equations

Electrochem ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 197-215
Author(s):  
Jerzy J. Jasielec
Keyword(s):  
Electrical Potential ◽  
Signal Propagation ◽  
Liquid Junction Potential ◽  
Liquid Junction ◽  
Patch Clamp Technique ◽  
Poisson Equations ◽  
Cellular Environment ◽  
Electrochemical Transport ◽  
Insight Into ◽  
Junction Potential

This work is aimed to give an electrochemical insight into the ionic transport phenomena in the cellular environment of organized brain tissue. The Nernst–Planck–Poisson (NPP) model is presented, and its applications in the description of electrodiffusion phenomena relevant in nanoscale neurophysiology are reviewed. These phenomena include: the signal propagation in neurons, the liquid junction potential in extracellular space, electrochemical transport in ion channels, the electrical potential distortions invisible to patch-clamp technique, and calcium transport through mitochondrial membrane. The limitations, as well as the extensions of the NPP model that allow us to overcome these limitations, are also discussed.

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