New plasma excitation sources for spectro-, micro-, and speciation analytical applications

The Applied Atomic Spectroscopy group of Dr. Buscher has strategically focused its forces on the development of new plasma excitation sources for the highly sensitive and element selective spectrometric analysis of the elements and their chemical species. The group’s research work particularly aims at the creation of the urgently needed highest performance detection systems for both trace and ultra-trace element analysis but also speciation analysis.

Element and trace element analysis has reached a development stage of high reliability in terms of analytical quality of the data achieved. However, the total concentration of elements in a real world sample is often not the information that is actually needed to assess the chemical, toxicological, physical and other properties connected with the elements in question. The different chemical species of the elements determine their partially largely varying properties. Tin is a good example element that demonstrates the general challenge quite well. Inorganic tin compounds are not known to show seriously harmful properties, while the organic compound tributyltin acts as an endocrine disruptor. Already in trace concentrations this tin species acts similarly to a pharmaceutical and has the power to interrupt important biochemical cycles in living organisms with possibly fatal impact. Conclusively, this element species is to be classified as highly bioactive substance. Therefore, speciation analysis – the qualitative and/or quantitative determination of one or more chemical species – is one of the great current challenges for analytical scientists worldwide. The analytical performance of the needed element selective detectors has to be extremely high to reach the challenging low limits of detection.

In the Applied Atomic Spectroscopy group the size of the innovative plasma excitation sources ranges from micrometer plasma discharges e.g. for analyses with optimized spatial resolution to the inductively coupled plasma (ICP) discharges of the Static High sensitivity ICP (SHIP) and the Universal MAss spectrometric detector for Speciation analysis (UMAS) inside the 2.8 cm load coil of an ICP.

Universal MAss spectrometric detector for Speciation analysis (UMAS)

Following the development of the SHIP torch for optical emission spectroscopy, the principle of the low flow-torch is currently being transferred to ICP-MS. This torch in meant to be used as a new powerful ion source for the highly sensitive mass spectrometric detection of chemical species. The concept of UMAS is to hyphenate different chromatographic or electrophoretic separation techniques to this new low-flow ion source for ICP-MS. Taking into account the long waiting times for the chromatographic runs, the waste of argon in hyphenated techniques with the conventional ICP-MS is even a multiple of the argon consumption in element analysis.

To develop this innovative plasma source, both the torch and also the sampler design had to be modified to allow efficient ion generation and sampling for mass spectrometry. In addition to the advantage of the low argon consumption, the analytical performance for the determination of non metals likes phosphorous and sulfur could be significantly improved compared to the conventional ICP-MS.

Involved group members: Thorben Pfeifer