TY  - JOUR
AU  - Bulska, E.
AU  - Wysocka, I. A.
AU  - Wierzbicka, M. H.
AU  - Proost, K.
AU  - Janssens, K.
AU  - Falkenberg, G.
AU  - DESY
TI  - In vivo investigation of the distribution and the local speciation of selenium in Allium cepa L. by means of microscopic X-ray absorption near-edge structure spectroscopy and confocal microscopic X-ray fluorescence analysis
JO  - Analytical chemistry
VL  - 78
SN  - 0003-2700
CY  - Columbus, Ohio
PB  - American Chemical Society
M1  - PHPPUBDB-3402
SP  - 7616-7624
PY  - 2006
AB  - In this work, microscopic X-ray absorption near-edge structure spectroscopy (mu-XANES) and confocal microscopic X-ray fluorescence analysis (mu-XRF) were used for the in vivo determination of the distribution of total selenium and for the local speciation of selenium in roots and leaves of onion. Selected Allium cepa L. plants were grown hydroponically in a standard medium containing inorganic selenium compounds (selenite or selenate). The measurements were performed in vivo, that is, on living plants without the need for any form of sampling or sample pretreatment and without the necessity for cutting plant tissues into pieces. Distinct energy differences of the XANES spectra of various selenium reference compounds having different oxidation states allow adjusting the excitation energies used for mu-XRF mapping in such a manner that the distribution of selenium in various oxidation states is obtained with a spatial resolution of a few tens of micrometers within the virtual cross section of the onion tissues. We find that the ratio of inorganic to amino acid selenium compounds differs in various subparts of the plant. Detailed in vivo investigation of the distribution of various selenium species in virtual cross sections of root tips and green leaf shows that the selenium transport takes place via different mechanisms, depending on the nature of the selenium compounds originally taken up.
KW  - Amino Acids: analysis
KW  - Microscopy, Confocal: methods
KW  - Microscopy, Fluorescence: methods
KW  - Onions: chemistry
KW  - Organoselenium Compounds: analysis
KW  - Oxidation-Reduction
KW  - Plant Leaves: chemistry
KW  - Plant Leaves: ultrastructure
KW  - Plant Roots: chemistry
KW  - Plant Roots: ultrastructure
KW  - Selenium: analysis
KW  - Spectrometry, X-Ray Emission: methods
KW  - Amino Acids (NLM Chemicals)
KW  - Organoselenium Compounds (NLM Chemicals)
KW  - Selenium (NLM Chemicals)
LB  - PUB:(DE-HGF)16
C6  - pmid:17105151
UR  - <Go to ISI:>//WOS:000242021400003
DO  - DOI:10.1021/ac060380s
UR  - https://bib-pubdb1.desy.de/record/81075
ER  -