Used as a colorimetric indicator in complexometric titrations, particularly for the detection of metal ions such as calcium, magnesium, and rare earth elements. It is especially effective in acidic to slightly acidic pH ranges, where it forms stable, brightly colored complexes with multivalent metal ions, changing from yellow to red or violet upon binding. Commonly employed in EDTA titrations to determine water hardness and in analytical chemistry for endpoint detection. Also utilized in spectrophotometric methods for quantitative metal analysis due to its distinct absorbance shift upon metal chelation.