Application of 4,5,6-trihydroxy-9-phenylfluorenes as analytical reagents

It has been stated that the compound of indium with pyrogallol red and diphenylguanidine can be extracted with n-pentanol from its aqueous solution at pH 7-8. The In-to-PGR-to-DPG molar ratio is 1:2:2 and the molar absorptivity of the complex at 530 nm epsilon=3.0.104. The Beer's law is satisfied in the indium concentration range from 0.2 to 1.3 μg/ml. The method was used for determination of indium in metallic copper and zinc on the level of 10-3%. (author)