LAUSR

An extremely simple, cost-effective and one-step method was developed for the preparation of solid-phase microextrac-tion (SPME) fibers via the in-situ synthesis of carbonaceous nanoparticles on the surface of stainless-steel fiber from a candle flame. The prepared SPME fiber provided excellent adsorption capability toward Hg2+ derived with sodium tetrae-thylborate and was explored for the separation, pre-concentration and long-term preservation of ultra-trace mercury in natural water samples. Moreover, the SPME fiber was further utilized for the highly sensitive routine analysis and filed analysis of mercury with a commercial atomic fluorescence spectrometer (AFS) and a miniature point discharge optical emission spectrometer (µPD-OES), respectively. Under the optimum conditions, detection of limits of 0.0005 µg L-1 and 0.007 µg L-1 together with relative standard deviations (RSDs) less than 5.8% were obtained for Hg2+ by headspace SPME-AFS and SPME-µPD-OES, respectively. The practicality of the prepared SPME fiber was validated via the determination of Hg2+ in real water samples with satisfactory recoveries (79%-115%). Long-term preservation of mercury at part per tril-lion level was undertaken at -20 °C and the sample loss rates were less than 5% after 9 days of storage, respectively, indi-cating that the storage performances of mercury provided by the proposed method are much better than that obtained by conventional method. Notably, the extraction performance of the SPME fiber is not decreased obviously even after more than 100 times of operation. Due to its advantages of high sensitivity, high stability, simple operation, low cost, and low energy consumption, this method provides an avenue for the field analysis and long-term preservation of mercury in the field of environmental analytical chemistry.