Blue O, Toluidine
Phenothiazin-5-ium, 3-amino-7-(dimethylamino)-2-methyl-, chloride
Toluidine Blue O
A phenothiazine that has been used as a hemostatic, a biological stain, and a dye for wool and silk. Tolonium chloride has also been used as a diagnostic aid for oral and gastric neoplasms and in the identification of the parathyroid gland in thyroid surgery.