Determination of trace molybdenum in biological and water samples by graphite furnace atomic absorption spectrometry after separation and preconcentration on immobilized titanium dioxide nanoparticles

A new method has been developed for the determination of trace molybdenum based on separation and preconcentration with TiO₂ nanoparticles immobilized on silica gel (immobilized TiO₂ nanoparticles) prior to its determination by graphite furnace atomic absorption spectrometry (GFAAS). The optimum experimental parameters for preconcentration of molybdenum, such as pH of the sample, sample flow rate and volume, eluent and interfering ions, have been investigated. Molybdenum can be quantitatively retained by immobilized TiO₂ nanoparticles at pH 1.0 and separated from the metal cations in the solution, then eluted completely with 0.5 mol L^?1 NaOH. The detection limit of this method for Mo was 0.6 ng L^?1 with an enrichment factor of 100, and the relative standard deviation (RSD) was 3.4% at the 10 ng mL^?1 Mo level. The method has been applied to the determination of trace amounts of Mo in biological and water samples with satisfactory results.