SIMULTANEOUS DETERMINATION OF COPPER, COBALT AND NICKEL BY HPLC AND SOLVENT-EXTRACTION WITH DIETHYLDITHIO CARBAMIC ACID AS REAGENT

Simultaneous quantitation of several components in a sample is alterna tive to the sequential determination. It avoids the separation on mask ing steps, simplifying the automatization of the analysis. The solvent extraction procedure is used for the determination of copper, cobalt and nickel simultaneously at microgram levels. The reagent diethyldith iocarbamic acid has been examined for the high performance liquid chro matographic c separation of copper(II), cobalt(II) and nickel(II) chel ates (range pH 9-11) on Reversed Phase High Performance Liquid Chromat ography (RP-HPLC) columns (150 x 3,9 mm) packed with Nova Pak C-18, 4 mu m. An aliquot of sample containing copper, cobalt and nickel in a m ixture was transferred to a well-stoppered test tube to which was adde d reagent [diethyldithiocarbamic acid 0,5% in ethanol:water (1:1), pH 10] and 10 ml organic solvent (ethyl ether). After shaking with mechan ical shaker for 5 min, the organic layer was separated and 20 mu l tra nsferred to another tube containing methanol (1ml). The methanolic sol ution (15 mu l) was injected, on the reversed phase HPLC column. The c omplexes are eluted with a binary mixture of methanol and water (75:25 ) at a now-rate of 0,5 mi min(-1). The detection is carried out with a UV detector at 260 mn. The method shows several adventages: short ana lysis time, minimized sample preparation, minimized effect of interfer ing ions, a low detection limit (50 ppb for nickel, 30 ppb for copper, and 5 ppb for cobalt) and good reproducibility, making it suitable fo r many types of samples, including alloys.