Application of cause-and-effect analysis to potentiometric titration

Area of Science:

• Analytical Chemistry
• Physical Chemistry
• Computational Chemistry

Background:

• Potentiometric titration is a fundamental technique for determining chemical properties.
• Accurate interpretation of titration data requires a robust uncertainty budget.
• Existing methods may not fully capture the complexities of measurement uncertainty.

Purpose of the Study:

• To apply the ISO and Eurachem measurement-uncertainty budget approach to potentiometric titration data.
• To evaluate protonation constants of arsenazo III within a defined pH range.
• To generate speciation diagrams with integrated uncertainty estimates.

Main Methods:

• Utilized a cause-and-effect diagram to map potential sources of uncertainty.
• Employed the Superquad software within a computer-intensive resampling framework.
• Applied empirical probability distributions and second-order confidence estimates for data interpretation.

Main Results:

• Successfully interpreted potentiometric titration data using the bottom-up uncertainty budget approach.
• Evaluated seven protonation constants for arsenazo III in the pH range of 2-10.7.
• Generated a speciation diagram incorporating reliable uncertainty estimates.

Conclusions:

• The study demonstrates the feasibility of a complete uncertainty budget approach for potentiometric titration.
• This methodology enhances the reliability of chemical speciation analysis.
• The developed approach provides a more rigorous framework for interpreting complex chemical data.