I. Spectrophotometric determination of gold with Di-2-pyridyl ketoxime. II. Spectrophotometric determination of palladium with Di-2-pyridyl ketoxime. III. Rapid spectrophotometric determination of cobalt with Di-2-pyridyl ketoxime. IV. Spectrophotometric determination of iron(II) with Di-2-pyridyl ketoxime. V. Rapid gravimetric determination of palladium with Di-2-pyridyl ketoxime

Part I. Di-2-pyridyl ketoxime has been found to be highly selective for gold; it reacted to form a water-soluble chelate which is extractable into dichloromethane. A molar ratio plot showed that the gold and the reagent combined in the ratio of 1 mole to 2 moles, respectively. The molar absorptivity of the gold chelate in dichloromethane was 2.1 x 10 4. Absorbance measurements were made at the wavelength of maximum absorbance, 459 mμ. Part II. A spectrophotometric method for the determination of microgram quantities of palladium with di-2-pyridyl ketoxime has been developed. Palladium reacts with the reagent to form a water-insoluble chelate which is extractable into chloroform. The result of analysis of the chelate showed that palladium and the reagent combined in the ratio of 1 mole to 2 moles. The chelate in chloroform exhibited an absorption maximum at 410 mμ and has a molar absorptivity of 1.2 x 104. The platinum group metals do not interfere and microgram quantities of gold can be tolerated. Interferences due to iron, copper, nickel, and cobalt can be masked with EDTA. Part III. A rapid spectrophotometric method for the determination of low levels of cobalt with di-2-pyridyl ketoxime is proposed. A 3:1 water-soluble complex which is easily extractable into chloroform and has an absorption maximum at 388 mμ forms instantaneously. Beer\u27s law is obeyed and the molar absorptivity is 19.5 x 103. An extensive investigation of the interference of 60 cations and anions shows the method to be widely applicable; it is simple, convenient and reproducible. Part IV. Di-2-pyridyl ketoxime has been proposed for the spectrophotometric determination of iron(II). The complex is stable and exhibits an absorption maxima of 534 mμ in an alkaline citrate medium. Beer\u27s law is obeyed and the molar absorptivity is 1.5 x 104. Large amounts of copper, nickel, and cobalt are tolerated. The method is simple, convenient and reproducible. Part V. Di-2-pyridyl ketoxime has been proposed for the gravimetric determination of palladium. The chelate is precipitated over a pH range of 3 to 11 and is weighed as Pd(C11H8N 3O)2. An extensive foreign ion study and analytical conditions for precipitation indicates the procedure to be widely applicable, rapid, and simple