Preconcentration of ultra-trace germanium in water samples with nano-sized TiO2 colloid and determination by GFAAS with colloid sampling

Abstract

A method for preconcentration and determination of ultra-trace germanium is presented in this work. Germanium (Ge(IV) in this work) in the water samples was preconcentrated by applying nano-sized TiO₂ colloid as adsorbent. When the pH values of solution were 6.0–8.0, the adsorption efficiency of nano-sized TiO₂ colloid for germanium reached 97.0 ∼ 99.0% in a short time. After centrifugation, the sediment which contained the concentrated Ge(IV) was inverted to colloid by adding HNO₃ of certain concentration. Ge(IV) in colloid was determined by graphite furnace atomic absorption spectrometry (GFAAS). In this study, germanium was approximately 20 times concentrated and a low detection limit (3σ) of 43 ng L⁻¹ was achieved. As the adsorbed Ge(IV) in colloid could be directly determined by means of GFAAS, desorption process was not needed, which simplified the process. This method was applied for the determination of ultra-trace germanium in water samples and satisfactory results were obtained.