Evaluation of Egorov's improved separate solution method for determination of low selectivity coefficients by...

Area of Science:

• Analytical Chemistry
• Electrochemistry
• Chemical Sensing

Background:

• Ion-selective electrodes (ISEs) are crucial for chemical analysis.
• Determining accurate selectivity coefficients for ISEs is challenging.
• Egorov et al. proposed a method using time-dependent selectivity coefficients.

Purpose of the Study:

• To critically evaluate the Egorov methodology for determining unbiased selectivity coefficients.
• To assess the influence of ion distribution on the method's effectiveness.
• To propose modifications for improved accuracy under specific conditions.

Main Methods:

• Finite element analysis (FEA) was employed to model ion diffusion.
• Simulations were performed under varying initial ion distributions.
• Time-dependent selectivity coefficients were analyzed computationally.

Main Results:

• The Egorov methodology significantly improves selectivity values with initially uniform ion distribution.
• FEA supports the principal assumption of square root of time diffusion layer progression.
• Extrapolation of logarithmic selectivity coefficients is more effective with strong inward primary ion fluxes.

Conclusions:

• The Egorov method is highly effective for initially uniform ion distributions.
• FEA validates the underlying diffusion model for specific conditions.
• A modified extrapolation approach enhances accuracy when primary ion influx is substantial.