Sensitivity and working range of backside calibration potentiometry.

Area of Science:

• Analytical Chemistry
• Electrochemistry
• Sensing Technology

Background:

• Introduced backside calibration potentiometry as a novel potentiometric sensing approach.
• Leverages the disappearance of the stir effect in supported liquid ion-selective membranes (SLMs) without ion-ionophore complex gradients.
• Ideal for applications requiring measurements without in-situ recalibration, such as remote monitoring.

Purpose of the Study:

• To establish a theoretical model for predicting the working concentration range of backside calibration potentiometry.
• To experimentally validate the theoretical model using lead(II)-selective membranes.
• To investigate the influence of interfering ions and membrane selectivity on the method's working range.

Main Methods:

• Development of a theoretical model to predict the operational concentration limits.
• Utilized lead(II)-selective Celgard membranes with H+ as the primary interfering ion.
• Measured electromotive force (emf) differences between stirred and unstirred solutions to assess the stir effect.

Main Results:

• The emf change magnitude exhibited a bell-shaped curve as a function of sample lead(II) concentration, spanning approximately three orders of magnitude.
• Interfering ion concentration and membrane selectivity significantly impacted the working range.
• Observed measurable emf changes even with a logarithmic concentration ratio of 0.05 for primary ions across the membrane.

Conclusions:

• The developed theoretical model accurately predicts the working concentration range for backside calibration potentiometry.
• The method is robust and effective for lead(II) detection over a wide concentration range, even with interfering ions.
• Experimental findings align well with theoretical predictions, confirming the model's utility.