Used primarily in water and wastewater analysis to determine color intensity. The solution serves as a reference standard in visual and instrumental color comparison methods, ensuring accurate and consistent measurement of sample color. Commonly applied in environmental testing laboratories, drinking water facilities, and industrial quality control to comply with regulatory standards. Provides a stable and reproducible color scale when assessing samples using the Platinum-Cobalt (Pt-Co) or Hazen color units. Also used in calibration of spectrophotometers and colorimeters for reliable results across multiple tests.