Eriochrome blue SE is primarily used as a complexometric indicator in analytical chemistry. It is particularly effective in the titration of metal ions, such as calcium and magnesium, in water hardness testing. The chemical forms a distinct color change when it binds to these metal ions, allowing for precise endpoint detection during titration. Additionally, it is employed in the dyeing and printing industries due to its ability to form stable complexes with metal ions, enhancing color fastness on fabrics. Its application extends to research laboratories for studying metal ion interactions and in environmental testing to assess metal contamination in water samples.