Used in analytical chemistry to detect and estimate fluoride ions in water and other samples. The solution works on the principle of color change due to the release of fluoride ions from a zirconium-alizarin complex, resulting in a visible shift from red to yellow when fluoride is present. Commonly applied in environmental testing, particularly for monitoring fluoride levels in drinking water and industrial effluents. Also used in laboratory quality control procedures where rapid, colorimetric detection of fluoride is required. Suitable for field testing due to its simple visual interpretation and minimal equipment needs.