The research heavily relies on commercially available ionophore membrane cocktails for some anions (Cl-, NO3, and HPO4), which may limit the generalizability of the findings and hinder reproducibility for researchers who might not have access to these specific cocktails. Furthermore, the lower anion selectivity and sensitivity compared to cations introduces greater uncertainty in anion concentration measurements, potentially affecting the accuracy of overall analyte analysis. The paper mentions that changes in ISFET performance would require recalibration of selectivity coefficients, but it does not offer specific guidelines or automated procedures for performing such recalibrations. This lack of clarity could pose challenges for practical implementation and long-term use of the sensor array.

While the separate solution method provides a straightforward way to estimate single-ion concentrations, it is less representative of real-world scenarios where multiple ions coexist. The reliance on numerical methods to solve for ion concentrations in multi-analyte solutions introduces computational complexity and potential inaccuracies, especially when dealing with non-ideal solutions or strong interference effects. The nonlinear nature of the Nikolskii-Eisenman equation can make it difficult to ensure unique and stable solutions, particularly in cases of low sensitivity or high cross-sensitivity.