Determination of Trace Elements in Mineral Water Using Total Reflection X‐Ray Fluorescence Spectrometry after Preconcentration with Ammonium Pyrrolidinedithiocarbamate

The determination of trace elements in mineral water by preconcentration with ammonium pyrrolidinedithiocarbamate (APDC) is described. Samples were spiked with an internal Ga standard and the precipitated dithiocarbamates of trace elements were separated by filtration through a Nuclepore filter. A small amount of the deposit obtained on the filter was transferred to a quartz reflector plate and analyzed by total reflection x-ray fluorescence (TXRF) spectrometry. The whole procedure was calibrated and tested with standard solutions of Fe, Ni, Cu, Zn and Pb in doubly distilled water in the concentration range 10-200 ng ml -1 . The method was applied to the analysis of mineral water. With the described procedure the absolute limits of detection were improved by about two orders of magnitude compared with the direct analysis of mineral water. The improvement in detection limits was mainly due to preconcentration of the above metals but also partly to the background reduction in the spectrum because of the removal of alkali and alkaline earth elements in the preconcentration process. The precision of elemental determinations on preconcentrated samples also improved relative to direct water analysis owing to the better counting statistics achieved in a 200 s acquisition of the respective spectra.