Optical sensor of anionic surfactants using solid-phase extraction with a lactone-form rhodamine B membrane.

Area of Science:

• Analytical Chemistry
• Materials Science
• Chemical Sensing

Background:

• Anionic surfactants are widely used but require sensitive detection methods.
• Existing detection techniques can be complex or lack real-time capabilities.
• Development of novel optical sensors offers a promising alternative for surfactant analysis.

Purpose of the Study:

• To develop and characterize a novel optical sensor for the selective detection of anionic surfactants.
• To investigate the sensing mechanism based on spectral changes in a Rhodamine B-modified membrane.
• To evaluate the sensor's performance with common anionic surfactants.

Main Methods:

• Fabrication of an optical sensing membrane using 2-nitrophenyloctyl ether-plasticized poly(vinyl chloride) and lactone-form Rhodamine B (L-RB).
• Investigation of the ion-pair coextraction mechanism involving anionic surfactants and protons into the PVC membrane.
• Spectrophotometric analysis to correlate color change (absorption maximum at 558 nm) with surfactant concentration.

Main Results:

• The optical membrane exhibited a distinct color change from light pink to dark pink upon interaction with anionic surfactants.
• The sensing mechanism was confirmed to involve ion-pair coextraction and the formation of an L-RB ion associate.
• The sensor demonstrated sensitivity to anionic surfactants like dodecylbenzenesulfonate, dodecylsulfate, and di-2-ethylhexyl sulfosuccinate.
• Effective detection was achieved in the concentration range of 1 to 50 microM.

Conclusions:

• A novel, colorimetric optical sensor for anionic surfactants has been successfully developed.
• The sensor utilizes a Rhodamine B-based membrane and relies on spectral changes for detection.
• The developed sensor shows potential for the sensitive and selective determination of common anionic surfactants.