A 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 medium is reported, utilizing an Al³⁺-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.