Monosegmented Flow Analysis Exploiting Aqueous Two-phase Systems for the Determination of Cobalt

An environmentally safe procedure has been developed for the extraction, separation and determination of metal ions using a monosegmented flow analysis technique that exploits an aqueous two-phase system (ATPS-MSFA). The ATPS-MSFA method was applied for the determination of cobalt, based on the reaction between Co(II) and KSCN, which produces a metallic complex that spontaneously partitions to the top phase of the ATPS composed of poly(ethylene oxide), ammonium sulfate and water. The linear range was 5.00 to 500 μmol kg−1 (R = 0.9998; n = 13) with a coefficient of variation equal to 1.14% (n = 7). The method yielded a limit of detection and a limit of quantification of 2.17 and 7.24 μmol kg−1, respectively. The ATPS-MSFA method was applied to the determination of cobalt in a nickel-cadmium battery sample and the results were validity with flame atomic absorption spectrometry using addition standard.