Gold-Modified TiO2 Nanotube Thin Film-based Purge & Trap Coupling with Microplasma Atomic Emission Spectroscopy for Determination of Trace Mercury in Water

A method coupling nano-gold, modified titanium dioxide (TiO2) nanotube thin film-based purge and trap (P&T) to miniature point discharge atomic emission spectrometry (mu PD-OES) for field detection of mercury in water was developed. In this system, Hg2+ in water sample was reduced to Hg0 by KBH4. Then, the generated Hg0 was trapped by the prepared thin film. The adsorbed Hg0 was rapidly desorbed by heating and subsequently swept into the excitation source of mu PD-OES for detection. The limit of detection (LOD) of this method was 0.79 ng/L, wherein the relative standard deviations (RSDs, n=11) of 20 ng/L and 100 ng/L standard Hg2+ solutions were 3.1% and 4.8%, respectively. The accuracy and practicality of the developed method were evaluated by analyzing a water certified reference material (CRM) and several environmental water samples with satisfactory recoveries of 84.5%- 103.0%. Compared with the conventional gold sand trapping method, the developed method was not only portable and cheap, but also had high analytical stability and reproducibility. By further coupling with a portable and low -energy consumption microplasma atomic emission spectrometer, the trace level of mercury in environmental water samples could be determined sensitively, accurately and rapidly, thus offering unique promising for on-site analysis.