separation and preconcentration trace amounts of nickel ion us-ing modified multiwalled carbon nanotubes sorbent prior to flame atomic absorption spectrometry determination

in this work, a selective method for separation and preconcentration of nickel ions at trace level on modified multiwalled carbon nanotubes columns and determination by flame atomic absorption spectrometry (faas) has been developed. multiwalled carbon nanotubes were oxidized with concentrated hno3 and then modified with loading 1-(2-pyridylazo)-2-naphtol. the sorption of ni(ii) ions was quantitative in the ph =9. elution of the adsorbed nickel was carried out with 5.0 ml of 0.1 mol l−1 hno3. the amount of eluted nickel was measured using flame atomic absorption spectrometry. factors influencing sorption and desorption of ni(ii) ions were investigated, including the sample ph, flow rates of sample and eluent solution, eluent type, breakthrough volume and interference ions. the relative standard deviation of the method was ±0.57% (n=8) and the limit of detection was 2.04   g ml−1 (3σb/m, n=8). the method was applied to the determination of ni(ii) in water samples and standard alloy (nkk. no. 920, aluminum alloy).