Used as a sensitive reagent for the detection and colorimetric determination of trace amounts of heavy metal ions, especially lead and mercury, in environmental, biological, and industrial samples. The solution forms colored complexes with these metals, allowing for visual or spectrophotometric analysis. Its use in solvent extraction enables selective separation of metals from complex matrices. Commonly applied in water quality testing, clinical toxicology, and metallurgical assays due to its high specificity and ease of use in field and laboratory settings.