Xylenol Orange disodium salt is widely used as a metallochromic indicator in complexometric titrations, particularly for the detection of metal ions such as calcium, magnesium, and rare earth elements. Its ability to form colored complexes with these metals makes it valuable in analytical chemistry for determining metal concentrations in various samples. In biological research, it is employed to study calcium dynamics in cells, aiding in understanding cellular processes. Additionally, it is utilized in environmental testing to assess water quality by detecting trace metal contaminants. Its sensitivity and specificity to metal ions make it a crucial tool in both laboratory and industrial settings.