Development of an Optode Detector for Determination of Anionic Surfactants by Flow Injection Analysis.

Area of Science:

• Analytical Chemistry
• Chemical Sensing
• Environmental Analysis

Background:

• Anionic surfactants (AS) are widely used in detergents and pose environmental concerns.
• Accurate and efficient methods are needed for AS determination in commercial products.
• Optode-based detection offers a sensitive approach for chemical analysis.

Purpose of the Study:

• To develop and demonstrate a flow-injection analysis (FIA) method for assaying anionic surfactants (AS).
• To utilize a novel optode detector for enhanced AS detection sensitivity and specificity.
• To validate the method for determining AS levels in real-world samples like laundry detergents.

Main Methods:

• Fabrication of an optode membrane using 2-nitrophenyl octyl ether, lactone form rhodamine B (L-RB), and poly(vinyl chloride).
• Integration of the AS optode into a flow-injection analysis (FIA) system for automated sample processing.
• Characterization of the optode's linear response range and sampling rate using standard AS solutions.

Main Results:

• The AS optode exhibited a linear response to AS in the concentration range of 20–100 μmol dm⁻³ within the FIA system.
• The proposed FIA system achieved a sampling rate of approximately 5 samples per hour for a representative AS ion (sodium dodecylbenzenesulfonate).
• The method was successfully applied to determine AS levels in commercially available laundry detergent samples.

Conclusions:

• The developed FIA method with an AS optode detector provides a viable approach for sensitive and accurate anionic surfactant quantification.
• This method demonstrates potential for routine analysis of AS in consumer products and environmental monitoring.
• The optode membrane composition and FIA system design contribute to the method's effectiveness.