This mixture of anions—fluoride, chloride, nitrate, and sulfate—is commonly encountered in environmental and industrial water systems. It is particularly relevant in wastewater analysis, where the presence of these anions indicates contamination from agricultural runoff, industrial discharges, or municipal sources. Fluoride and chloride are often monitored in drinking water to ensure safety and compliance with health standards. Nitrate detection is critical in assessing eutrophication potential in water bodies and identifying fertilizer or sewage contamination. Sulfate levels are important in evaluating corrosion potential in pipelines and the suitability of water for industrial use, such as in boilers or cooling systems. Ion chromatography using this anion mix is a standard method for simultaneous determination of these ions in environmental, food, and pharmaceutical samples. The combination also serves as a calibration standard for analytical instruments, ensuring accurate quantification in routine testing.