Preconcentration of ultra-trace arsenic with nanometre-sized TiO2 colloid and determination by AFS with slurry sampling

Abstract

This study describes a united method for the analysis of ultra-trace arsenic in environmental water samples by preconcentration of TiO₂ colloid and determination of Atomic Fluorescence Spectrometry (AFS). When the pH values of solution are between 6.0 and 7.0, the adsorption for arsenic is above 98.0% with the dosage of nanometre-sized TiO₂ colloid (0.2%) being 6.0 mL. Without desorbing the concentrated arsenic, the precipitated TiO₂ is directly inverted to colloid after centrifugation. Arsenic is then determined by AFS with slurry sampling. This united method is simple, fast and sensitive. The detection limit (3σ) and the relative standard deviation (R.S.D) of this method are 10.6 ng L⁻¹ and 7.04% (n = 6), respectively. When the method is applied to the determination of ultra-trace arsenic in environmental standard samples, the results are in good agreement with the standard values. And when it comes to environmental samples, satisfactory results are obtained.