Nitroso R Salt is widely used as a reagent in analytical chemistry, particularly for the detection and quantification of metal ions. It is especially effective in identifying cobalt, forming a distinct red-colored complex that can be measured spectrophotometrically. This property makes it valuable in environmental testing, where it helps monitor cobalt levels in water and soil samples. Additionally, it is employed in industrial quality control processes to ensure the purity of metal products. Its ability to selectively bind with specific metals also aids in research studies involving metal ion behavior and interactions.