Used as a metal ion indicator in complexometric titrations, particularly for the detection of trivalent metal ions such as aluminum, iron, and chromium. It is especially effective in EDTA titrations where it provides a clear color change from yellow to red or violet upon binding with metal ions. Commonly applied in water hardness testing and in analytical chemistry for the determination of metal concentrations in solution. Also used in biochemical and environmental assays where selective metal ion detection is required.