Used as a fluorescent derivative in analytical methods for the detection and quantification of thiamine (vitamin B1) and its phosphate esters in biological samples. Its strong fluorescence allows sensitive measurement in complex matrices like blood, urine, and food products. Commonly employed in high-performance liquid chromatography (HPLC) with fluorescence detection, where thiamine is oxidized to thiochrome to enhance detectability. Also applied in enzymatic assays and stability studies of vitamin B1 in pharmaceuticals and fortified foods.