Titration of strong and weak acids by sequential injection analysis technique

Area of Science:

• Analytical Chemistry
• Chemical Analysis
• Titration Methods

Background:

• Traditional acid-base titration methods can be time-consuming and require manual adjustments.
• There is a need for automated and versatile titration techniques for various acid concentrations.

Purpose of the Study:

• To develop and validate a sequential injection analysis (SIA) method for acid-base titrations.
• To demonstrate the method's applicability for both strong and weak acids across a wide range of concentrations.

Main Methods:

• Sequential injection analysis (SIA) utilizing sequential aspiration of sample and reagent zones into a carrier stream.
• Detection of unneutralized base using an LED-spectrophotometer based on indicator color change.
• Implementation of automatic sample dilution for high-concentration samples.

Main Results:

• A linear relationship was established between peak area and the logarithm of acid concentration for strong acids (10⁻⁴–10⁻² M and 0.1–3 M).
• Accurate titration of weak acids like acetic acid was achieved in the concentration range of 3x10⁻⁴–8x10⁻² M.
• The method demonstrated adaptability for different acids and concentration ranges by adjusting injected volumes.

Conclusions:

• The developed SIA titration method offers a robust and adaptable approach for automated acid-base analysis.
• The technique provides good linearity and accuracy for diverse acid samples, minimizing manual intervention.
• SIA titration presents a valuable alternative for routine chemical analysis requiring precise acid concentration determination.