The suitability of a newly developed, portable total reflection X-ray fluorescence (TXRF) spectrometer (PicoTAX, Roentec, Berlin, Germany) to analyze trace elements in biological material was tested and compared with a stationary instrument (Spectrometer 8030 C, FEI, Munich, Germany). For that, single freshwater microcrustacean specimens (Daphnia spec.) with dry weights ranging between 1.6 and 18.8 μg individual⁻¹ were prepared according to the dry method and analyzed with both instruments. Additionally, for orientation purposes, freshly collected Daphnia were prepared in field according to the wet method directly on the glass carrier and analyzed using the portable PicoTAX. For method validation, certified reference material (CRM 414, plankton) was analyzed.

The results of the in-field measurements demonstrate that the PicoTAX yields very fast and sufficiently sensitive in-field measurements on the element content of minute biological samples. For As, Cu, K, Mn, Ni and Sr, a good correlation was found between the two spectrometers. Only for Ca, Fe, Pb and Zn the comparison with the results of the stationary equipment has shown significant differences.