Research Group Leopold


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Research Interests

The development of analytical methods for trace and ultra trace analysis of elements, element species, and nanoparticles is in focus of our research. For this purpose, new flow injection analysis systems (FIAS) and solid phase extraction techniques (SPE) are developed and coupled to or combined with various atomic spectrometry techniques for trace element detection, such as atomic fluorescence spectrometry (AFS), atomic absorption spectrometry (AAS), atomic emission spectrometry (AES), total reflection X-ray fluorescence spectrometry (TXRF), micro-X-ray fluorescence spectrometry (µXRF). Furthermore, nanomaterials play an important role – both, as tool to enhance analysis and as target analyte. Our research projects always include validation and application to real world samples coming from environmental, biological or medical research and application.

Current Topic: Mercury Trace Analysis

Mercury is an increasing and persistent pollutant and is due to its high mobility globally distributed in our environment. Because of its high toxicity it requires monitoring in all environmental compartments, however, it is particularly important in the hydrosphere, where mercury bio-accumulates up to a million times in the aquatic food chain. Mercury concentrations in natural waters are typically in the sub to low ng L-1 range and extremely sensitive detection techniques are required to obtain reliable analytical data. Our research in this field yields at enhancing the analytical performance and at the same time providing sustainable and easy to handle in-situ and reagent-free analytical procedures on basis of nanomaterials. In recent years we have designed new solid phase extraction (SPE) materials based on gold nanoparticles that serve as catalysts for degradation of mercury species and at the same time as selective adsorbers for mercury traces by amalgamation. This preconcentration technique is highly efficient and selective and can be coupled to several atomic spectrometry detection technique achieving extremely low detection limits of a few fg absolute.

    Current Projects:

  • NanoTeHg Developing new Nanogold-based Test Strip for Environmental and Bio-Monitoring of Mercury (Hg) Traces; in Cooperation with Prof. Dr. Mika Lindén, UUlm, funded by DFG
  • Development of preconcentration techniques applicable to stable isotope analysis of mercury in seawaters by multi collector ICP-MS; in cooperation with Prof. Dr. Frank Vanhaecke, UGhent
  • Enhancing speciation analysis of mercury by combining SPE preconcentration and chromatographic separation techniques

Current Topic: Metal nanoparticle analysis

MNPs are nowadays widely used and represent a new kind of challenging analytes in product quality control, medical research, as well as in food and environmental analysis. For the later, low concentrations in combination with very complex matrices pose problems to the analytical chemist. In particular, standard sample pretreatment techniques for trace analysis fail in the investigation of MNPs, since unintended size changes are often observed. Therefore, no robust and valid methods for detection and characterisation of MNP in complex samples are established at presence. Our research strategy therefore aims at a direct detection and size characterisation of NP in complex matrices, i.e. without sample pretreatment using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS-GFAAS). Recently we have introduced a unique approach to detect and characterise silver and gold nanoparticles by HR-CS-GFAAS applying a novel strategy for interpretation of signals. This method has the potential to solve the analytical problems involved with standard sample pretreatment methods and enables to distinguish metal ions from metal nanoparticles at low concentrations in complex matrices.

    Current Projects:

  • DiDeSiNa Direct Detection of Silver Nanoparticles in biological and environmental samples; funded by DFG
  • SizNAAS Sizing of metal nanoparticles by graphite furnace atomic absorption spectrometry (GFAAS)
  • Evaluation of the atomisation mechanism of metal nanoparticles in GFAAS; funded by YERUN

Current Topic: Trace bio-metal analysis

Trace elements are essential for life and many trace metals have been identified to play a crucial role in diseases like cancer or Alzheimer. In order to achieve a better understanding of their homeostasis and involvement in diseases as well as to find potential new diagnostic tools, the development of novel and enhanced methods for trace analysis of these metals in biological and medical samples is important. This includes amongst others the provision of analytical methods for trace metal determination in minute sample amounts and analysis of tissues or cells with lateral resolution (elemental imaging). In this field, we are interested in the development of new methods applying X-ray fluorescence spectrometry techniques.

    Current Projects:

  • SuperResXRF Super Resolution techniques in µ-X-ray fluorescence spectrometry, in cooperation with Prof. Dr. Henning Bruhn-Fujimoto, UUlm, funded by Vector-Stiftung
  • Enhancing iron trace analysis in biomedical research using total reflection X-ray fluorescence spectrometry, in cooperation with Prof. Dr. Maja Vujic Spasic, UUlm