Sequential flow injection determination of chlorine species using a triiodide-selective electrode detector

Area of Science:

• Analytical Chemistry
• Environmental Chemistry

Background:

• Residual chlorine species are crucial indicators of water quality and disinfection efficacy.
• Accurate speciation of these compounds is essential for environmental monitoring and public health.

Purpose of the Study:

• To develop a flow injection analysis (FIA) method for simultaneous determination of combined available chlorine (CAC), free available chlorine (FAC), total available chlorine (TAC), and chlorite (ClO2-).
• To apply kinetic discrimination and pH manipulation for effective speciation of residual chlorine species.

Main Methods:

• Utilized a flow-through triiodide-selective electrode as the detector.
• Employed kinetic discrimination of reactions with Fe2+ for speciation of FAC, CAC, and TAC.
• Adjusted carrier stream pH to differentiate and determine available chlorine species and chlorite.

Main Results:

• Achieved linearity for active chlorine determination from 2.8 x 10(-6) to 2.8 x 10(-4) M, with a detection limit of 1.4 x 10(-6) M.
• Demonstrated method selectivity through pH-dependent iodide oxidation and potentiometric selectivity coefficients.
• Successfully applied the method to analyze chlorine species in tap water and disinfecting formulations.

Conclusions:

• The developed FIA method provides a reliable and selective approach for determining multiple residual chlorine species.
• The method offers a valuable tool for water quality assessment and disinfection efficacy monitoring.
• The findings support the use of this technique in routine analysis of environmental and commercial samples.