Used in environmental testing to calibrate instruments for measuring nitrate levels in water samples, ensuring accurate detection of contamination in drinking water, wastewater, and agricultural runoff. Commonly applied in laboratories for quality control in spectrophotometric and ion chromatography analyses. Also utilized in agricultural research to assess soil and irrigation water quality, helping optimize fertilizer use and prevent over-enrichment of ecosystems. Suitable for routine calibration of field test kits and automated monitoring systems in water treatment plants.