Trace Element Speciation Laboratory

There are very few known natural organofluorine compounds, but there are hundreds of man-made organofluorine compounds. Besides the widely known use in Teflon and other plastics, fluorinated groups are often used in drugs to influence their physiological retention.

These man-made compounds are bioaccumulative in fatty tissue and can have harmful effects. Relatively little is known about the metabolism of fluorinated compounds. The main reason for this is the difficulty in identifying unknown fluorinated compounds. Fluorinated compounds are difficult to distinguish from non-fluorinated compounds by organic mass spectrometry and are usually not detectable by elemental detectors.

Our team is working on new methods for fluorine detection using ICPMS as a fluorine-specific detector. Fluorine forms polyatomic ions, which could be a possible method for the detection of unknown fluorine compounds. We also use CIC (combustion ion chromatography) offline and online with other chromatographic techniques for non-targeted detection of fluorinated compounds. Another applied method is molecular absorption spectrometry (HR-GF-MAS), which determines fluorine as a polyatomic molecule. These methods can be used as complementary methods to HPLC-ICPMS / ESI-MS. Currently, our work is focused on method development and method robustness testing.

The aim of this work is on the one hand to quantify fluorine-containing compounds of unknown structure, e.g. degradation products of drugs and pesticides, sensitively, quickly and efficiently. On the other hand, it is expected that new fluorine-containing metabolites or compounds can be identified more quickly with the aid of a coupling of HPLC-ICPMS and ESI-MS. It is also expected that the degradation of environmentally relevant fluorine compounds can be monitored in detail using these methods.

In addition, we are working on the determination of known fluorinated compounds in water bodies, wildlife (wild boar, whales, chamois) as early warning signs of human exposure by means of fluorine mass balance (TF, EOF, TOP assay, targeted analysis and non-targeted analysis) using CIC, HR-GFMAS, ICPMS, LC-MS/MS, LC-HPLC-ICPMS/ESI-HRMS by means of HPLC-ESI-MS.

Arsenic is the element whose distribution and metabolism we study the most. It is not only a known carcinogen and toxic in its inorganic forms, but also occurs in nature in a variety of organic forms with variable toxicity.

Among other things, we are working on the distribution of inorganic arsenic in various food and feedstuffs. One of the main areas we are working on together with other research groups is the determination of inorganic arsenic in rice. The amount of inorganic arsenic in rice depends very much on the growing conditions. Laboratory-based experiments and field experiments show that changes in the irrigation regime and the addition of fertilizers can influence the arsenic content. Findings from the research of our and other groups were decisive for the introduction of the maximum permitted levels of inorganic arsenic in rice products in the EU in 2015. Information on arsenic, its distribution, species and existing regulations can be found in our publication on analytical aspects of arsenic speciation in food and feed legislation.

In this context, the development of simple and specific determination methods for inorganic arsenic is also important. For the food industry in particular, it is important that the inorganic arsenic content of rice, for example, can be determined on site; we have validated a method specifically for this purpose that allows on-site evaluation of the harvest using very simple means and are working on the further development of this method.

Elements are not homogeneously distributed in tissue and also show different distribution patterns at the cellular level. The same applies to organic molecules such as proteins and metabolites. Bio-imaging involves the determination of the elemental or molecular distribution pattern. The combination of elemental and molecular distribution with histologic information allows a correlation between pathology, proteins and metal concentrations. Bio-imaging with laser ablation ICPMS can reveal this inhomogeneity of elemental distribution and also provide clues to disease mechanisms.

Imaging of fungal infected tissue, for example, revealed that the iron and copper distribution changes due to infection and also indicated that the host tries to fight the infection by changes in copper metabolism. In contrast, a bacterial infection showed a significant increase in calcium in the infected area with a simultaneous decrease in all other essential elements.

We are interested in identifying naturally occurring nanoparticles (NNPs).

One research avenue is the detoxification of mercury by forming an agglomeration with selenium in Grindwalle liver, kidney and brain. Here, FFFF-ICP-MS and sp-ICP-MS as well as XANES/EXAFS were used to characterize these NNPs.

We also use AF4 with non-aqueous media and determined mercury sulfides in gas condensates from the oil and gas industry.

Ongoing projects include the determination of natural nanoparticles in biological tissues such as the organs of whales and birds of prey. This information can be the key to identifying detoxification mechanisms of toxic elements such as mercury and arsenic, using FFFF-ICP-MS, laser ablation ICP-MS and NanoSIMS. Furthermore, we are working on the determination of nanoplastics in biological and environmental samples, especially fluorine-containing nanoparticles in environmental and biological samples by fluorine mapping using LA-ICPMS and single particle ICPMS (spICPMS).

Mercury in all its molecular forms is toxic. We are working on:

• The development of industrially applicable methods of mercury speciation in collaboration with PS-Analytics, London.
• We are studying the metabolism of mercury compounds in the marine ecosystem.
• Risk assessment of mercury contamination in oil and gas refineries during operation and after decommissioning.

The determination of inorganic mercury and its two methylated forms is required in a variety of sample types. The standard method for quantification is a complicated and time-consuming procedure. In this method, mercury is derivatized in all its forms and then detected by ICP-MS after gas chromatographic separation. We have developed an HPLC cold vapour atomic fluorescence spectrometry method that does not require derivatization and is capable of detecting the major natural mercury compounds in a variety of sample types. This method uses an online enrichment step that allows detection limits at the pg/L level (ppq).