Application of some calibration strategies in comparison to determine Cr, Ni, Cu, Zn, As, and Pb in contaminated plants by wavelength dispersive x‐ray fluorescence

The study of nonstandard samples wherein their element compositions differ from those of routine samples motivates analysts to look for new methodological approaches. To determine the high concentrations of Cr, Ni, Cu, Zn, As, and Pb in polluted plants, the authors applied wavelength dispersive x‐ray fluorescence (WDXRF), using three calibration strategies in comparison. The following sets of calibration samples were tested: available plant and biological CRMs; synthetic samples; and “house reference materials” (HRMs). The synthetic samples were prepared, adding small portions of the loose sediment CRMs to a plant CRM. The polluted plant samples, analyzed by atomic absorption spectrometry and inductively coupled plasma mass spectrometry, were used as HRMs to construct the calibration curves and validate XRF results. It was ascertained that all three calibration strategies can be used to quantify above elements in contaminated plants, providing different precision of WDXRF results. The calibration procedure with HRMs has provided the least errors in the element determinations. Calibration with synthetic samples causes larger errors due to some differences in chemical compositions between calibration and analyzed samples as well as due to probable errors in the synthetic sample preparation. The calibration with plant and biological samples is of limited applicability in XRF of contaminated plants by reason of narrow content ranges of some elements.