Used as a sensitive analytical reagent for the colorimetric detection of trace metals, particularly copper and zinc. Forms highly colored complexes that allow for visual or spectrophotometric determination at low concentrations. Commonly applied in environmental monitoring, industrial quality control, and research settings where precise metal ion detection is required. Its strong chromogenic response makes it suitable for use in test strips and sensor formulations. Also explored in dye-sensitized systems and as a precursor in the development of optical sensors due to its stable color change properties.