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Title: Evaluation of specimen preparation techniques for micro-PIXE localisation of elements in hyperaccumulating plants
Authors: Kachenko, AG
Siegele, R
Bhatia, NP
Singh, B
Ionescu, M
Keywords: Plants
Biological localization
Biological accumulation
PIXE analysis
Issue Date: Apr-2008
Publisher: Elsevier
Citation: Kachenko, A. G., Siegele, R., Bhatia, N. P., Singh, B., & Ionescu, M. (2008). Evaluation of specimen preparation techniques for micro-PIXE localisation of elements in hyperaccumulating plants. Nuclear Instruments & Methods in Physics Research Section b-Beam Interactions with Materials and Atoms, 266(8), 1598-1604. doi:10.1016/j.nimb.2007.11.017
Abstract: Hybanthus floribundus subsp. floribundus, a rare Australian Ni-hyperaccumulating shrub and Pityrogramma calomelanos var. austroamericana, an Australian naturalized As-hyperaccumulating fern are promising species for use in phytoremediation of contaminated sites. Micro-proton-induced X-ray emission (μ-PIXE) spectroscopy was used to map the elemental distribution of the accumulated metal(loid)s, Ca and K in leaf or pinnule tissues of the two plant species. Samples were prepared by two contrasting specimen preparation techniques: freeze-substitution in tetrahydrofuran (THF) and freeze-drying. The specimens were analysed to compare the suitability of each technique in preserving (i) the spatial elemental distribution and (ii) the tissue structure of the specimens. Further, the μ-PIXE results were compared with concentration of elements in the bulk tissue obtained by ICP-AES analysis. In H. floribundus subsp. floribundus, μ-PIXE analysis revealed Ni, Ca and K concentrations in freeze-dried leaf tissues were at par with bulk tissue concentrations. Elemental distribution maps illustrated that Ni was preferentially localised in the adaxial epidermal tissues (1% DW) and least concentration was found in spongy mesophyll tissues (0.53% DW). Conversely, elemental distribution maps of THF freeze-substituted tissues indicated significantly lower Ni, Ca and K concentrations than freeze-dried specimens and bulk tissue concentrations. Moreover, Ni concentrations were uniform across the whole specimen and no localisation was observed. In P. calomelanos var. austroamericana freeze-dried pinnule tissues, μ-PIXE revealed statistically similar As, Ca and K concentrations as compared to bulk tissue concentrations. Elemental distribution maps showed that As localisation was relatively uniform across the whole specimen. Once again, THF freeze-substituted tissues revealed a significant loss of As compared to freeze-dried specimens and the concentrations obtained by bulk tissue analysis. The results demonstrate that freeze-drying is a suitable sample preparation technique to study elemental distribution of ions in H. floribundus and P. calomelanos plant tissues using μ-PIXE spectroscopy. Furthermore, cellular structure was preserved in samples prepared using this technique. © 2007, Elsevier Ltd.
Gov't Doc #: 1393
ISSN: 0168-583X
Appears in Collections:Journal Articles

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