Used as a sensitive chromogenic reagent in analytical chemistry for the detection and spectrophotometric determination of trace metal ions, especially copper(II), nickel(II), and cobalt(II). It forms highly colored complexes with these metals, allowing for precise measurement at low concentrations. The sharp color change upon complexation makes it valuable in colorimetric assays and environmental monitoring of heavy metals in water and soil samples. Also applied in the development of test strips and sensors due to its visible response to metal ion presence.