WP2: Multielemental and Isotopic Analysis
The aim of this WP is to develop methods for multielemental trace
element analysis with results traceable to the SI.
We set the requirements for measurement uncertainty at < 5%, high
throughput (analysis time < 1 Min), low sample consumption (µL range)
and minimum sample preparation to provide methods suitable according to good
clinical practice (GCP).
The ultimate goal will be the validation of the methods according to the
eurachem guidelines, and the interlaboratory comparison within the
consortium partners.
Results
To investigate the influence of metals and metalloproteins in the development of AD, sensitive and accurate measurement procedures were developed within the project, mainly using inductively coupled plasma spectrometry (ICP-MS). ICP-MS provides excellent capabilities for the determination of metal concentrations in biological samples and also for the elemental detection of proteins containing a metal or heteroatom (metalloproteins or metal-containing proteins). ICP-MS is also characterised by its high sensitivity and specificity, its multielement capability to monitor simultaneously the different metals or heteroatoms associated/bound to a protein. It provides direct isotopic information (which allows isotopic ratio and isotopic dilution analysis) and it is versatile and easy to be coupled to separation methods such as high-performance liquid chromatography (HPLC) or field-flow fractionation (FFF). Therefore, the development of hyphenated separations with ICP-MS elemental detection (mainly HPLC-ICP-MS) has been the analytical tool for conducting speciation studies to underpin clinical measurements in this project.
Methods for high throughput accurate quantification of multiple trace elements in biological fluids and tissues meeting the demands of the highly regulated clinical environment are of utmost importance. The careful balance of trace element concentrations in human body fluids and tissues is essential for maintaining the optimal homeostasis to avoid adverse side effects of excess metal exposure and/or depletion. While for serum and blood, reference levels are fairly well established for most trace elements and serve as important diagnostic parameters, limited data is available for elemental concentrations in CSF. CSF plays an important role in the homeostasis and metabolism of the central nervous system. The consortium implemented, compared and presented different ICP-MS methods for low sample volume, high-throughput multielement analysis in biological fluids including CSF. For this latter sample matrix, due to the lack of certified reference material, open vessel digestion in combination with sectorfield-ICP-MS analysis was used as gold standard to establish a reference data set. Owing to the low sample volume and trace element concentrations of CSF, flow injection methods with 5 µL sample intake were developed integrating matrix matched calibration concepts and ID (Theiner et al.; Analyst 2019, Theiner et al.; JAAS 2019).