Solid Phase Extraction of Ultra Trace Amounts of Cobalt and Nickel on Octadecyl Bonded Silica Membrane Disk Modified with N,N?-Bis(3,5-di-tert-butylsalicylidene)- 1,2-diaminoethane and Determination by Inductively C

Abstract

A highly sensitive and accurate method for preconcentration   and determination of ultra trace amounts of cobalt and   nickel ions in water samples is proposed. The preconcentration   is achieved using C_18^-silica extraction disks modified with   N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminoethane   (H₂L₁). The retained ions on the prepared solid phase was   eluted with 10 mL of nitric acid (0.01 M) and measured by   inductively coupled plasma-optical emission spectrometry   (ICP-OES). The influence of the type and amount of eluent   used, pH, sample and eluent flow rates, amount of H₂L₁ and   the effect of other ions on extraction efficiency were investigated.   The limits of detection of the method were 0.2 and   0.09 μg L^-1 for cobalt and nickel, respectively and provide an   enrichment factor of 100. The results obtained on 10 successive   extractions and elution cycles revealed relative standard   deviations of 1.9 and 1.8 % for cobalt and nickel, respectively.   The proposed method has been applied to the determination   of ultra trace amounts of cobalt and nickel ions in natural and   synthetic water samples with satisfactory results.