Spectrophotometric determination of isonaphthazarin impurity in 1,4-dioxo-2,2,3,3-tetrahydroxy-1,2,3,4-terahydronaphthalene (tetraxolin)

A quantitative spectrophotometric method has been developed for determining the impurity of isonaphthazarin in samples of tetraxolin. The relative error of determination is about 1.0% at a confidence probability of P = 0.95%. The procedure is recommended for the quantitative control of the possible impurity of isonaphthazarin in the parent substance of tetraxolin. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 41, No. 1, pp. 38–40, January, 2007.