Used as a sensitive chromogenic reagent for the spectrophotometric detection and determination of trace metal ions, especially copper(II), nickel(II), and cobalt(II). It forms highly colored complexes with these metals, allowing for quantitative analysis in environmental, biological, and industrial samples. The sharp color change upon complexation makes it suitable for use in analytical methods where visual or instrumental detection is required. Also applied in the development of test strips and sensors due to its selective response to specific metal ions in solution.