Authors:S. Lehmann, G. Geipel, G. Grambole, and G. Bernhard
Heavy metals like the actinides possess a high risk potential to the environment not only because of their radiotoxicity but
also due to their chemical toxicology. Uranium as one of the major actinide elements has to be considered in particular. Under
reducing conditions, tetravalent uranium occurs primarily in the environment. To date, a lack of appropriate analytical techniques
that featured sufficient sensitivity made it difficult to study the aqueous phosphate chemistry of uranium(IV) as such complexes
show only low solubility. A novel time-resolved laser fluorescence spectroscopy system was set up recently and optimized to
do research on uranium(IV). By application of this laser system we could successfully study uranium(IV) phosphate in concentration
ranges where no precipitation or formation of colloids occurred. At pH = 1.0, U4+ and one uranium(IV) phosphate complex existed in parallel in aqueous solution. The complex could be identified as [U(H2PO4)]3+. Determination of its corresponding complex formation constant via two different evaluation methods resulted in the finding
. Both values prove that [U(H2PO4)]3+ is a very stable complex in solution under experimental conditions. As they are in very good agreement with each other, the
total complex formation constant was determined by means of the weighted average out of (1) and (2). It was calculated to
Authors:T. Ossaka, K. Kakegawa, T. Oi, and M. Mukaida
Determination of major elements in natural solid samples by X-ray fluorescence spectroscopy (XRF) with a fusion disc technique is described. Data obtained by the present XRF analytical system were found to have satisfactorily high reliability. Five rock samples and a volcanic ash sample with varying ages ranging from the present to 180 000 years, derived by the current and past volcanic activities in the Unzen area, Nagasaki, Japan were analyzed for their major elements' compositions using the above mentioned system. The chemical composition of the magma under this area has changed very little at least over the last 180 000 years.
The complex formation of curium(III) with L2-aminobutyric acid was characterized by time-resolved laser-induced fluorescence
spectroscopy (TRLFS) at trace Cm(III) concentrations (3·10−7 M). The various curium(III) species, MpHqLr, identified are characterized by their individual luminescence spectra and luminescence lifetimes. The following formation
constants were determined log β101 = 5.17±0.07, log β102 = 9.00±0.07, and log β103 = 11.30±0.09 at ionic strength I = 0.5M. Possible structures of the curium aminobutyrate species will be discussed on the basis of the luminescence lifetime
measurements and the magnitude of the formation constants.
Authors:Erzsébet Háznagy-Radnai, Klára Pintye-Hódi, Szilvia Czigle, Tamás Martinek, Gábor Janicsák, Imre Máthé, and István Erős
We have isolated five iridoids (harpagide, acetylharpagide, harpagoside, ajugoside, and aucubin) from
L. by a combination of chromatographic methods-NP-TLC, RP-HPLC, and TLC-densitometry. The isolated iridoids were identified on the basis of their physical and spectroscopic properties. Basic information about their structures was obtained from their NMR spectra. X-ray fluorescence spectroscopy can be used for direct determination of inorganic elements in the leaves, stems, and inflorescences of
L. We identified K, Ca, Mo, Fe, Co, Ir, Ga, Tl, and S.
Two complimentary spectroscopic techniques, X-ray absorption and fluorescence spectroscopy have been conducted at spatial
scales of 1 to 25 μm on uranium contaminated soil sediments collected from two former nuclear materials processing facilities
of the DOE: Fernald, OH and Savannah River Site, SC. A method of imbedding particles in a non-reactive Si polymer was developed
such that individual particles could be examined before and after extraction with a wide range of chemicals typically used
in sequential extraction techniques and others proposed forex situ chemical intervention technologies. Using both the micro-X-ray fluorescence (XRF) and micro-X-ray Absorption Near Edge Structure
(XANES) techniques, both elemental and oxidation state distribution maps were generated on individual particles before and
following chemical extraction. XANES can determine the relative proportion of U(VI) and U(IV) in phases comprising individual
particles before and after extraction and showed that greater than 85% of the uranium existed as hexavalent U(VI). Fluorescence
spectra of contaminated particles containing mainly U(VI) revealed populations of uranyl hydroxide phases and demonstrated
the relative efficacy and specificity of each extraction method. Correlation of XAS and fluorescence data at micron scales
provides information of U oxidation state as well as chemical form in heterogeneous samples.
The use of X-ray tube fluorescence spectrometer with composite secondary target radiator is explained. Experimentally measured efficiencies and detection limits for coal samples are presented and discussed.
Authors:M. Nagj, J. Makjanić, I. Orlić, S. Tomić, and V. Valković
The X-ray spectrometric method for uranium determination in sea water is discussed. Two techniques of uranium enrichment are presented: (1) precipitation with the chelating agent ammonium-1-pyrrolidine dithiocarbamate (APDC) in the presence of iron(II) as a carrier and (2) complexation with APDC followed by adsorption on activated carbon. The best pH range and the other optimized conditions for uranium determination in sea water with both methods are reported.
Analysis by Energy Dispersive X-Ray Fluorescence (ED-XRF) technique of liquid samples and specimens in aqueous media requires that the sample chamber be flushed with helium gas. Moreover the sample should also be covered with mylar foil to hold the sample. The helium environment and the X-ray beam but also affect the sensitivity of different elements. An investigation was carried out with six multielement NBS standards to evaluate the effect of helium environment and mylar foil on the sensitivity of various elements. The effect of both the factors can be employed to improve the results of liquid samples with ED-XRF technique.
. & Czinkota, I.,
1993. Hot water percolation (HWP): A new rapid soil extraction method. Plant and Soil.
Senesi N., Miano T. M. & Proverzano, M. R.,
1991. Fluorescencespectroscopy as a means of