Perylene tetracarboxylate dye-based colorimetric and fluorometric sensor for ppb-level fluoride detection in water

Abstract

Fluoride contamination in water is a serious global concern that demands advanced sensing and quantitative monitoring methodologies. However, many existing fluoride sensors are limited to detecting fluoride ions in an organic medium. Herein, a novel approach developed using a perylene tertacarboxylate dye (K₄PTC) offers a solution. This method employs colorimetric and fluorescence signals to detect fluoride ions in an aqueous medium, showcasing high sensitivity, selectivity, and reversibility. The method primarily involves addition of AlCl₃ to the K₄PTC solution, resulting in diminished fluorescence, accompanied with a visible colour change. Subsequent addition of fluoride to the aforesaid solution triggers fluorescence restoration and colour reversal, forming the basis for fluoride ion sensing. Changes in absorbance and fluorescence intensity exhibit linear correlation with fluoride concentrations, enabling precise detection with remarkably low limits of detection of 0.2 ppm and 1 ppb for UV-vis and fluorescence techniques, respectively. This sensing methodology is successfully applied to detection of fluoride in ground water samples collected from fluoride-affected areas, highlighting its potential for rapid and accurate environmental monitoring and public health protection.