Developing new Nanogold-based Test Strip for Environmental and Bio-Monitoring of Mercury (HG) Traces - NANOTEHG -

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Even though industrial countries have made great efforts to reduce Hg emission over the last 25 years, global anthropogenic emission still increases slightly. Its excessive use in small-scale gold mining and increasing emissions from coal-fired power plants contribute mainly to Hg discharges. Therefore, this highly toxic heavy metal is still one of the most critical environmental pollutants. Consumption of fish is nowadays considered as the main source for general human Hg exposure. However, high occupational exposure still occurs for gold miners and workers in industry in developing countries. Hence, environmental as well as bio-monitoring of Hg traces is mandatory in order to prevent negative effects on humans.Although there are various highly sensitive and selective analytical methods available for Hg determination, these have several disadvantages, like consumption of highly toxic reagents, time-consuming sample preparation, and bulky instrumentation. Hence, further development in order to provide simplified procedures for rapid monitoring of Hg traces in real-world samples is required. The aim of the project is to develop a robust and valid analytical method for determination Hg traces in aqueous samples, like natural waters, human urine, acidic/basic extracts, etc. For this purpose, a test strip will be prepared that is dipped for a few minutes into a liquid sample in order to accumulate Hg. The probe will consist of a meso-porous silicon film on a silicon wafer containing gold nanoparticles in its pores. Selective and highly efficient accumulation of Hg onto this nanogold-modified thin film takes place after catalytic decomposition of all dissolved Hg species into Hg0 and subsequent amalgamation. Other than with common passive sampling approaches no deployment in the field/sample is planned. Furthermore, filling the pores of the test strip with organic solvents prior to dipping into the sample shall provide species-specific accumulation of Hg. Desorption of Hg from the probe will be performed thermally omitting the necessity of any leaching reagents. Hg0 vapour is detected by atomic fluorescence spectrometry. Regeneration of the catalytic active gold nanoparticles is achieved by this heating step, too. Hence, the complete analytical procedure will work reagent-free with a re-useable test strip, providing crucial advantages, such as simple and low-cost on-site handling and at the same time providing high sensitivity and selectivity. Therefore the new method will be a very valuable tool for environmental and bio-monitoring.