Pyrocatechol violet (PV) excellent quality manufacturer, supplier and exporter. Pyrocatechol violet (PV) is a sulfone phthalein dye made from condensing two moles of pyrocatechol with one mole of o-sulfobenzoic acid anhydride. PV has indicator properties and forms complexes with metal ions, making it useful as a chelometric reagent. As it chelates metals, a generally blue to blue-violet complex forms. Cationic surfactants, such as cetylammonium bromide significantly shift the absorbance maximum to higher wave lengths due to the formation of a higher ligand-to-metal ratio. Negatively charged chelates can be extracted into an immiscible solvent as an ionpair.