LJPcalc is a free and open source liquid junction potential (LJP) calculator that runs entirely in the browser. LJPcalc calculates LJP according to the stationary Nernst-Planck equation. This strategy is typically regarded as superior to the simpler Henderson equation used by most commercial LJP calculators, especially for solutions containing polyvalent ions.
If you enjoy LJPcalc, consider citing it by name: Liquid junction potential was calculated according to the stationary Nernst–Planck equation (Marino et al., 2014) using LJPcalc (RRID:SCR_025044).
Search "LJPcalc" on Google Scholar to see publications that cite LJPcalc.
LJPcalc was created by Scott Harden as a C#/.NET adaptation of the Java application JLJP originally written by Doriano Brogioli as described in Marino et al., 2014.
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LJP Theory and Calculation Tips - A collection of information related to LJP I put together while working on this project.
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Marino and Brogioli, 2016 - Analytical Results on the Behavior of a Liquid Junction across a Porous Diaphragm or a Charged Porous Membrane between Two Solutions According to the Nernst–Planck Equation
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Beaumont 1991 - Comparison of Henderson's Method I and restricted maximum likelihood estimation of genetic parameters of reproductive traits
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Marino et al. (2014) - describes a computational method to calculate LJP according to the stationary Nernst-Planck equation. The JAVA software described in this manuscript is open-source and now on GitHub (JLJP). Figure 1 directly compares LJP calculated by the Nernst-Planck vs. Henderson equation.
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Perram and Stiles (2006) - A review of several methods used to calculate liquid junction potential. This manuscript provides excellent context for the history of LJP calculations and describes the advantages and limitations of each.
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Shinagawa (1980) "Invalidity of the Henderson diffusion equation shown by the exact solution of the Nernst-Planck equations" - a manuscript which argues that the Henderson equation is inferior to solved Nernst-Planck-Poisson equations due to how it accounts for ion flux in the charged diffusion zone.
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Lin (2011) "The Poisson The Poisson-Nernst-Planck (PNP) system for ion transport (PNP) system for ion transport" - a PowerPoint presentation which reviews mathematical methods to calculate LJP with notes related to its application in measuring voltage across cell membranes.
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Nernst-Planck equation (Wikipedia)
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Goldman Equation (Wikipedia)
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EGTA charge and pH - Empirical determination of EGTA charge state distribution as a function of pH.
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LJPCalcWin - A Program for Calculating Liquid Junction Potentials
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LJP Corrections (Axon Instruments Application Note) describes how to calculate LJP using ClampEx and LJPCalcWin and also summarizes how to measure LJP experimentally
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LJP Corrections (Figl et al., AxoBits 39) summarizes LJP and discusses measurement and calculation with ClampEx