QUANTIFYING LEAD CONCENTRATIONS IN PLANT SAMPLES FROM A PHYTOREMEDIATION STUDY UTILIZING A PXRF

A review of literature on the determination of heavy metal contamination in the environment showed several different methods being used to extract and quantify lead concentrations in soil and plant samples. Atomic absorption spectrometry with Aqua Regia extraction is a popular method among many researchers because it ensures total lead extraction from the samples. However, the XRF has an advantage over the AAS with Aqua Regia because it is a rapid, nondestructive method for elemental analysis. The XRF has been shown to be a reliable analytical tool that can be verified with other destructive methods. The purpose of this study was to assess these two methods, AAS with Aqua Regia and XRF, for lead analysis of contaminated soil and plant samples. For this study, Chinese cabbage (Brassica chinensis) was grown in soils contaminated with different concentrations of lead. A pXRF was used to quantify the total concentration of lead in the plant shoots and soils after each sample was crushed to a powder. Lead concentrations in the plant and soil samples were then quantified using both graphite furnace and a flame atomic absorption spectrometer. Preliminary results showed that the methods were comparable and yielded similar results. The XRF results were within 12% of the AAS with Aqua Regia results. Soil lead concentrations did not differ significantly between the Aqua Regia-extracted lead analyzed with the AAS (443 ppm) and the concentrations obtained using the XRF method (486 ppm).