Constant Potential Coulometric Measurements with Ca²⁺-Selective Electrode: Analysis Using Calibration Plot vs....

Area of Science:

• Electrochemistry
• Analytical Chemistry
• Chemical Sensing

Background:

• Traditional analysis of calcium ions (Ca2+) often relies on calibration plots.
• Constant potential coulometric mode offers an alternative analytical approach.
• Ion-selective electrodes are crucial tools for quantifying specific ions in solution.

Purpose of the Study:

• To explore charge curve fitting as a novel analytical method in constant potential coulometric mode.
• To compare the efficacy of charge curve fitting against traditional calibration plot analysis.
• To investigate the impact of an electronic capacitor on measurement speed and accuracy.

Main Methods:

• Utilized a calcium ion (Ca2+) selective electrode as a model system.
• Performed analysis in pure calcium chloride (CaCl2) solutions.
• Compared charge curve fitting with calibration plot analysis, with and without an electronic capacitor in series.

Main Results:

• Both charge curve fitting and calibration plot methods yielded good results (within 2% error) when concentration differences were within three-fold.
• Larger concentration variations led to increased errors (10-25%) for both techniques.
• Incorporating an electronic capacitor significantly accelerated the electrode's response time.

Conclusions:

• Charge curve fitting is a viable alternative to calibration plots for Ca2+ analysis in constant potential coulometric mode.
• The accuracy of both methods is dependent on the ratio between initial and final concentrations.
• Electronic capacitors enhance the practical application of ion-selective electrodes by improving response speed.