Determination with ion selective electrodes in the low-level, non-Nernstian response region

Data analysis for concentration measurements in the nonlinear response region of ion-selective electrodes

“…Among the few published methods for doing this are the graphical calibration methods and the methods by Midgley (3), Parthasarathy et al (4), and Frazer et al (5) of inherent errors associated with nonlinear graphical interpolation, the graphical methods are not very accurate. The methods by Midgley and Parthasarathy et al involve assumptions about the electrode slope and standard electrode potental which lead to error in concentration measurements.…”

“…A method has been suggested by Midgley (6) for measurements in the region of limiting linear response, at concentrations near the detection limit, but it has a very limited range of applicability. The method by Frazer et al (5) is the only available method which can estimate concentrations in the nonlinear region to an acceptable degree of accuracy. However, because of the requirements of complex and expensive experimental equipment and extensive computing time, it is not suitable for routine measurements.…”