Used in environmental testing laboratories to calibrate instruments and validate analytical methods for measuring sulfide levels in water. Ensures accuracy and reliability in monitoring water quality, especially in wastewater treatment plants, industrial discharges, and natural water bodies. Helps maintain compliance with environmental regulations by providing a consistent reference for sulfide concentration. Commonly used in colorimetric and electrochemical analyses where precise sulfide detection is critical. Supports quality control programs in public health and environmental protection efforts.