Nano TiO2-based preconcentration for the speciation analysis of inorganic selenium by using ion chromatography with conductivity detection

A simple, sensitive, and cost-effective analytical method was developed for the speciation analysis of inorganic selenium by combining a nano-TiO2 preconcentration with an ion chromatography-conductivity detection (IC-CD) system. The experimental conditions for the simultaneous adsorption and desorption of Se(IV) and Se(VI) were carefully investigated. Under the established optimum condition, the Se(IV) and Se(VI) ions could been simultaneously adsorbed onto the nano-TiO2 surface at pH 4.0, and then effectively desorbed by 0.1 M sodium hydroxide eluent. The adsorption process was fast and reached adsorption equilibrium within 10 min. The nano-TiO2 also exhibited high adsorption capacity with 11.3 mg g(-1) for Se(IV) and 8.34 mg g(-1) for Se(VI). The enrichment factors for Se(IV) and Se(VI) were calculated to be 39 and 30, respectively, with sample volume of 50 mL. The detection limits (3 sigma) were 0.8 mu g L-1 for Se(IV) and 0.4 mu g L-1 for Se(VI), which were sensitive enough for the routine analysis of water and drink samples. The relative standard deviation was calculated to be <4% (n = 6) for detection of 30 mu g L-1 Se(IV) and 30 mu g L-1 Se(VI). The results of the present work confirmed that our developed nano-TiO2-IC-CD method could be applied for the detection of inorganic selenium species in tap water and drink samples with good recoveries in the range of 82%-108%. (C) 2011 Elsevier B.V. All rights reserved.