This demands the use of analytical techniques capable of analysing selenium at low concentrations with high
accuracy in widespread matrices and sometimes smallest sample amounts.
In connection with the increasing importance of selenium, there is a need for rapid and simple on-site (or
near-to-site) selenium analysis in food basics like wheat at processing and production sites, as well as for the
analysis of this element in dietary supplements. Common analytical techniques like electrothermal atomic
absorption spectroscopy (ETAAS) and inductively-coupled plasma mass spectrometry (ICP-MS) are capable
of analysing selenium in medical samples with detection limits in the range from 0.02 to 0.7 μg/l. Since in
many cases less complicated and expensive analytical techniques are required, TXRF has been tested
regarding its suitability for selenium analysis in different medical, food basics and dietary supplement
samples applying most simple sample preparation techniques.
The reported results indicate that the accurate analysis of selenium in all sample types is possible. The
detection limits of TXRF are in the range from 7 to 12 μg/l for medical samples and 0.1 to 0.2 mg/kg for food
basics and dietary supplements. Although this sensitivity is low compared to established techniques, it is
sufficient for the physiological concentrations of selenium in the investigated sample