An embodiment provides A method for measuring fluoride concentration in an aqueous solution, including: preparing a metal-ligand complex, wherein the metal-ligand complex comprises chromeazurol S and aluminum; placing the metal-ligand complex in a sample containing fluoride, wherein the placing generates a color change by releasing the chromeazurol S from the metal-ligand complex; and measuring, using colorimetric techniques, a concentration of fluoride within the sample, wherein the measuring comprises measuring an absorbance wavelength of a colorimetric ligand. Other embodiments are described and claimed.