Vg. Rodriguez et al., SIMULTANEOUS DETERMINATION OF COPPER, COBALT AND NICKEL BY HPLC AND SOLVENT-EXTRACTION WITH DIETHYLDITHIO CARBAMIC ACID AS REAGENT, Analytical letters, 27(7), 1994, pp. 1399-1406
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.