Fluorescein Based Dual Optical Sensor for Highly Selective and Sensitive Fluoride Detection in 100 % water medium

Abstract

A highly selective dual optical sensor for fluoride detection in 100% aqueous media is reported, utilizing an Al³⁺-mediated complex of fluorescein. The sensor exhibits distinct colorimetric and fluorometric responses, achieving detection limits of 0.7 ppm (UV-Vis) and 40 ppb (fluorescence). This method, validated on water samples and cellulose paper strips, offers a practical, low-cost approach for routine fluoride monitoring.