Used as a selective colorimetric reagent for the detection and quantification of copper(I) ions in aqueous solutions. It forms a stable, intensely colored complex with Cu⁺, allowing sensitive measurement in biological and environmental samples. Commonly applied in enzymatic assays where copper interference must be monitored or controlled. Also utilized in analytical chemistry to assess reducing agents that generate Cu⁺ from Cu²⁺. Its water solubility and specificity make it suitable for use in buffer systems and diagnostic kits.