Comparison of Usefulness of Four Chelating Agents (EDTA, NTA, ODA and IDA) for the Chromatographic Separation of Micro and Macro Amounts of Rare Earth Elements.

Literature on the use of four chelating agents namely: ethylenediaminetetraacetic acid, nitrilotriacetic acid, diglycolic acid and iminodiacetic acid for the chromatographic separation of micro and macro amounts of rare earth elements was critically reviewed and supplemented with some new unpublished data from our Laboratory. Advantages and disadvantages of ion exchange chromatography both in cation and anion mode as well as ion interaction chromatography techniques, which were used for rare earth elements separation, are discussed. The usefulness of some of the chromatographic systems for micro-macro separations was discussed and demonstrated.

New reversed phase-high performance liquid chromatographic method for selective separation of yttrium from all rare earth elements employing nitrilotriacetate complexes in anion exchange mode.

Separation of Y from other rare earth elements (REE) is difficult because of similarity of its ionic radius to ionic radii of Tb, Dy and Ho. In the new RP-HPLC system with C18 column, tetra-n-butyl ammonium hydroxide (TBAOH) as an ion interaction reagent (IIR), nitrilotriacetic acid (NTA) as a complexing agent at pH=2.8-3.

Inductively coupled plasma mass spectrometry in comparison with neutron activation and ion chromatography with UV/VIS detection for the determination of lanthanides in plant materials.

Analytical performance of inductively coupled plasma mass spectrometry (ICP-MS) for determination of lanthanides in plant materials was investigated and compared with neutron activation analysis (NAA) as well as ion chromatography (IC) with UV-VIS detection. Two sample preparation protocols were tested: (i) microwave assisted digestion by concentrated nitric acid; (ii) microwave digestion involving silica and fluoride removal, followed by the selective and quantitative lanthanides group separation from the plant matrix. Several Certified Reference Materials (CRM) of plant origin were used for the evaluation of the accuracy of the applied analytical procedures.

Two new reference materials based on tobacco leaves: certification for over a dozen of toxic and essential elements.

The preparation, certification, and characterization of two new biological certified reference materials for inorganic trace analysis have been presented. They are based on two different varieties of tobacco leaves, namely, Oriental Basma Tobacco Leaves (INCT-OBTL-5), grown in Greece, and Polish Virginia Tobacco Leaves (INCT-PVTL-6), grown in Poland. Certification of the materials was based on the statistical evaluation of results obtained in a worldwide interlaboratory comparison, in which 87 laboratories from 18 countries participated, providing 2568 laboratory averages on nearly 80 elements.

Comparison of performance of INAA, RNAA and ion chromatography for the determination of individual lanthanides.

Lanthanides represent an interesting group of elements which are steadily gaining importance in science and in industry. Literature data suggest that they may have a role in regulating cellular processes and also in agriculture enhancing plant growth. Only few instrumental methods like NAA, ICP-OES and ICP-MS have potential for the determination of low levels of all lanthanides, but in practice they often have to be combined with suitable separation/preconcentration methods to achieve maximum number of elements being determined and to assure good accuracy and precision.

RNAA in metrology: A highly accurate (definitive) method.

The idea of highly accurate (definitive) methods by radiochemical neutron activation analysis (RNAA) is presented and illustrated with several examples of methods worked out in this Laboratory over the past several years. Definitive methods by RNAA are constructed by combining reactor neutron activation with very selective and quantitative post-irradiation separation of the indicator radionuclide by column chromatography followed by gamma-ray spectrometric measurement. All conditions for the determination of the individual element are optimized and uncertainties associated with every step of the analytical procedure are minimized.

Metrological assessment of the high-accuracy RNAA method for determination of cobalt in biological materials.

The paper summarizes work on the development of the high-accuracy RNAA method for the determination of trace amounts of cobalt in biological materials. The method is based on a combination of neutron activation with selective and quantitative isolation of the analyte in a state of high radiochemical purity by use of column chromatography followed by gamma-ray spectrometric measurements. The method was devised according to a set of rules, which were formulated to obtain high accuracy of the method.

Preparation and use of reference materials for quality assurance in inorganic trace analysis.

A general preparation and certification scheme used in the Institute of Nuclear Chemistry and Technology (INCT) for the preparation and use of certified reference materials (CRMs) for inorganic trace analysis is presented and contrasted with approaches used by other CRM producers. 'Definitive' and 'very accurate' methods have a role, based on a combination of neutron activation and quantitative and selective post-irradiation isolation of an indicator radionuclide by column chromatography. Natural matrix CRMs of biological origin including the typical food products are reviewed and the need is identified for new well-characterized materials that would also be suitable for micro-analytical techniques such as PIXE, EDXRF, SS-AAS, etc.

Some difficult problems still existing in the preparation and certification of CRMs.

Differences between particle size measurements of CRMs by various methods are discussed and the importance of the reliability of such data for proper estimation of the homogeneity of the material is emphasized. On the basis of a very simple model, the dependence of the Ingamells' sampling constant on the average mass of a single particle of the material is derived, and theoretical predictions are compared with the experimental results. Various approaches to the certification of the candidate RMs are briefly reviewed.

Accurate determination of cobalt traces in several biological reference materials.

A newly devised, very accurate ("definitive") method for the determination of trace amounts of cobalt in biological materials was validated by the analysis of several certified reference materials. The method is based on a combination of neutron activation and selective and quantitative postirradiation isolation of radiocobalt from practically all other radionuclides by ion-exchange and extraction chromatography followed by gamma-ray spectrometric measurement. The significance of criteria that should be fulfilled in order to accept a given result as obtained by the "definitive method" is emphasized.

A comprehensive study on the contents and leaching of trace elements from fly-ash originating from Polish hard coal by NAA and AAS methods.

In order to assess the environmental risks associated with the emission of fly-ash into the atmosphere and its storage on waste heaps, the trace element contents of fly-ashes from burning Polish hard coal were determined by a newly developed INAA method. Leaching of trace elements from the fly-ash by water and H2SO4 solution (pH approximately 2.5) simulating acid rain, respectively, was studied using AAS and spectrophotometric methods.

Hair zinc and copper concentration in survivors of myocardial infarction.

Increased Zn/Cu ratio in the diet, and consequently in the body, was suggested to be of importance in the pathogenesis of atherosclerosis. Head hair of 29 male survivors of myocardial infarction and of 23 control males was studied for the concentration of Zn and Cu. The Zn hair concentration and Zn/Cu ratio in survivors of myocardial infarction was significantly higher in comparison with controls.