Used primarily as a reagent in analytical chemistry for the determination of nitrite and nitrate ions. It reacts with sulfanilic acid to form a diazo compound, which then couples with this chemical to produce a colored azo dye. This reaction is widely employed in spectrophotometric methods for water quality testing, ensuring safe drinking water by detecting harmful levels of nitrites. Additionally, it is utilized in environmental monitoring to assess nitrate pollution in soil and water bodies. Its stability and sensitivity make it a reliable choice for quantitative analysis in various laboratory settings.