Used as a sensitive reagent in extraction-spectrophotometric and fluorimetric methods for the determination of soft metal ions such as copper, silver, mercury, and cadmium in various samples. It forms highly colored or fluorescent complexes with these metals, enabling their detection at trace levels. Commonly applied in environmental analysis, industrial quality control, and metallurgical research where selective and sensitive detection of low-concentration metal ions is required. Its chelating properties enhance selectivity, especially in complex matrices, making it valuable in separation and pre-concentration techniques prior to instrumental analysis.