Used in environmental testing to calibrate instruments for measuring sulfide levels in water and wastewater. Commonly applied in industries such as oil and gas, pulp and paper, and wastewater treatment to monitor sulfur compounds that can cause corrosion, odor, or toxicity. Also used in laboratory research to develop and validate analytical methods like ion chromatography and colorimetric assays. Ensures accuracy in detecting sulfide concentrations for regulatory compliance and process control.