Cadion 2B is a metallochromic indicator used in analytical chemistry for the colorimetric and complexometric determination of heavy metal ions, particularly cadmium, zinc, and other transition metals. It forms stable colored complexes with these ions in aqueous solutions, typically exhibiting a color change from yellow (free dye) to red or magenta at the endpoint, enabling precise quantification in spectrophotometric methods and titrations. This reagent is valuable for environmental monitoring of cadmium in water, heavy metal analysis in pharmaceuticals, and industrial quality control. Its high sensitivity and selectivity make it ideal for laboratory applications requiring accurate detection of trace metal contaminants.