Application of modified multiwalled carbon nanotubes as a sorbent for simultaneous separation and preconcentration trace amounts of Au(III) and Mn(II).

A solid phase extraction procedure is proposed for simultaneous separation and preconcentration trace amounts of Au(III) and Mn(II) in an aqueous medium by using a column of multiwalled carbon nanotubes modified with the analytical reagent N,N'-bis(2-hydroxybenzylidene)-2,2'(aminophenylthio)ethane. An implementation, it was found that the sorption is quantitative in the pH range 5.0-7.5, whereas quantitative desorption occurs instantaneously with 4.0 mL of 0.1 mol L(-1) Na(2)S(2)O(3.) Selected elements were also determined by flame atomic absorption spectrometry. Linearity was maintained between 0.2 ng mL(-1) to 25 microg mL(-1) for gold and 0.08 ng mL(-1) to 5 microg mL(-1) for manganese in the original solution. Various parameters such as the effect of pH, flow rate, type and amount of eluent, breakthrough volume and interference of a large number of anions and cations on the recovery of the selected ions was studied. Under optimum conditions, the detection limits (3s, n=10) for analytes were 0.03 ng mL(-1) (gold) and 0.01 ng mL(-1) (manganese). The method was successfully applied for separation and determination of gold and manganese ions in water and standard samples.