Application of X-ray fluorescence spectrometer with two low-power X-ray tubes to analysis of environmental and biological materials

The energy-dispersive X-ray fluorescence spectrometer with two low-power X-ray tubes is presented together with a method of the determination of trace concentrations of several elements in water and biological materials. The spectrometer comprises a measuring head with two low-power X-ray tubes, high voltage supply, Si/Li detector and 12-position sample changer. The device is coupled to multichannel analyzer with printer and paper tape puncher. For the determination of Fe, Ni, Cu, Zn, Mn, Pb and Se at ppb level a preconcentration is used. The metal ions are separated from water by precipitation with sodium diethylditiocarbamate (NaDDTC). Selenium is reduced to its elemental form, with tellurium as a carrier after biological material had been decomposed. The estimated limit of detection is 20 ng/cm2 for Se, Ni, Cu, Zn and 40 ng/cm2 for Mn, Pb and Fe what corresponds to concentration 1 and 2 ppb respectively for a sample volume 250 cm3. Precision of the method amounts 4 to 25 per cent (st. dev.) depending on the element concentration. (author)