Studies on Hydroxyfluoran and Its Derivatives as Organic Reagents. IX : Determination of Rare Earth Elements with 3, 4, 5, 6-Tetrachloro-3', 4', 5', 6'-tetrahydroxyfluoran Methyl Ester

Examinations were made on the chelate titration of 3, 4, 5, 6-tetrachloro-3', 4', 5', 6'-tetrahydroxyfluoran methyl ester (Cl-gall-CH3) using rare earth elements (La, Ce, Pr, Sm, Nd, Y, Gd), and absorption photometric determination of rare earth elements using cetylpyridinium bromide and Cl-gall-CH3. It was thereby found that rare earth elements can be determined by absorption spectrophotometry, in the amount approximately 0-4 μg/ml, by using Cl-gall-CH3-rare earth element complex (2 : 1 molar coordinate) with the metal reagent of La, Ce, and Y, at pH 7.1, using absorptions at 655 mμ (Ce), 660 mμ (Gd), and 670 mμ (La, Pr, Sm, Nd, Y).