Determination of gold by nanometer titanium dioxide immobilized on silica gel packed microcolumn and flame atomic absorption spectrometry in geological and water samples

A new method has been developed for the determination of gold based on separation and preconcentration with a microcolumn packed with nanometer TiO₂ immobilized on silica gel (immobilized nanometer TiO₂) prior to its determination by flame atomic absorption spectrometry. The optimum experimental parameters for preconcentration of gold, such as pH of the sample, sample flow rate and volume, eluent and interfering ions, have been investigated. Gold could be quantitatively retained by immobilized nanometer TiO₂ in the pH range of 8-10, then eluted completely with 0.1 mol L⁻¹ HNO₃. The detection limit of this method for Au was 0.21 ng mL⁻¹ with an enrichment factor of 50, and the relative standard deviation (R.S.D.) was 1.8% at the 100 ng mL⁻¹ Au level. The method has been applied for the determination of trace amounts of Au in geological and water samples with satisfactory results.