This mixture of anions—chloride, bromide, nitrate, and sulfate—is commonly encountered in environmental and industrial water systems. It is particularly relevant in water quality analysis, where the combined presence of these ions can indicate contamination from seawater intrusion, industrial discharge, or agricultural runoff. Chloride and sulfate contribute to water salinity and corrosion potential in pipelines, making their monitoring critical in drinking water and cooling systems. Nitrate is a key indicator of nutrient pollution, often from fertilizers or wastewater, and its detection is essential for assessing risks to human health and aquatic ecosystems. Bromide, though typically present in lower concentrations, is significant in disinfection processes, as it can react with disinfectants to form harmful brominated disinfection byproducts. Analytical methods such as ion chromatography use standardized mixtures of these anions for calibration, enabling accurate quantification in environmental and industrial samples. The mixture also serves as a reference in desalination research, helping evaluate the efficiency of removal processes like reverse osmosis or ion exchange.