Chromotropic acid sodium salt is widely used as a reagent in analytical chemistry for the detection and quantification of formaldehyde. It forms a colored complex with formaldehyde in the presence of sulfuric acid, which can be measured spectrophotometrically, making it a key component in environmental monitoring, industrial hygiene, and assessing formaldehyde levels in air, water, food, and consumer products such as textiles. Additionally, it is employed in the determination of other aldehydes and ketones in various chemical and biochemical analyses. In organic synthesis, it serves as a building block for the preparation of more complex compounds, particularly in the development of dyes and pigments.