Electrochemistry (EC) coupled to mass spectrometry (MS) in the last years has been proven to serve as a promising tool in the field of metabolism research. In conventional animal based metabolism studies, the identification of especially short living, reactive intermediates is difficult due to their binding to cell components such as proteins. With EC/MS as a purely instrumental approach, most oxidative metabolism reactions can be simulated. This way, it is possible to study the phase I metabolism of xenobiotics including the identification of reactive intermediates. By extending the setup and adding a solution of a biomolecule like a peptide, protein or DNA immediately after EC oxidation, the phase II metabolism can be studied and toxicity assessment can be performed as well.
Uwe Karst is Professor of Analytical Chemistry at the University of Münster in Germany. His research interests focus on hyphenated analytical techniques and their (bio)medical and pharmaceutical applications, including elemental speciation analysis, metallomics, mass spectrometric imaging and electrochemistry/MS.
Chemical imaging of biological tissues
Chemical imaging has emerged as an important field of research in recent years, and the respective methods are used for the spatially resolved analysis of the elemental and molecular composition of biological or pharmaceutical samples. Here, three different techniques for elemental and molecular imaging including µXRF, LA-ICP-MS and LA-APCI-MS are presented with their major principles and applications.
An elemental species is defined as a particular binding form or oxidation state of the element. The toxicity of a chemical element like Hg, Se or As is not dependent on the total elemental concentration, but rather on the concentration of its respective toxic species. In order to access species information with high sensitivity and selectivity, hyphenated techniques with chromatographic separation and mass spectrometric detection are applied.
The concept of speciation analysis is presented for the example of gadolinium-based contrast agents for magnetic resonance imaging, which are discharged in the aquatic environment via the wastewater. In this case, hydrophilic interaction liquid chromatography (HILIC) is combined with electrospray mass spectrometry (ESI-MS) for species identification and inductively coupled plasma-mass spectrometry (ICP-MS) for species quantification.