TERNARY COMPLEXES IN SPECTROPHOTOMETRIC DETERMINATION OF TRACE AMOUNTS OF PLATINUM(4)

A simple, rapid, reproducible, sensitive and selective method is proposed for the spectrophotometric determination of submicrogram amounts of platinum(IV) in aqueous media. The proposed method involves the formation of a ternary complex between the hexa-ammine-platinum(IV) cationic complex, and the counter-ion 2,4,5,7-tetrabromofluorescein ethyl ester. The reaction is instantaneous and the red ternary complex remains stable for ca. 1 hr. Beer's law is obeyed over the range 39-1170 ppM with molar absorptivity of ca. 8.0 × 104 at 555 nm and pH 10. A relative standard deviation of 1.1% was found for the reproducibility of the method. Even without the use of masking agents, no interference is encountered from other noble metals except rhodium(III). Of 13 other cations and 8 anions tested, only iron(III) interferes. © 1969.