Heavy element chemistry facilities at Texas A&M University

A new program to study the chemistry of the homologs of the transactinide elements is under development, and is centered at the Texas A&M University Cyclotron Institute. New facilities have been designed and/or implemented to enable this research. These include equipment for the production of lanthanide and other targets, a rotating target wheel, an improved recoil transfer chamber, and a customized on-line radiochemical laboratory. Additional target development is being performed at Argonne National Laboratory. The new facilities and equipment are discussed.     

Environmental,toxicological and biomedical research on trace metals: Radiochemical separations for neutron activation analysis

Twenty-two radiochemical separation procedures for neutron activation analysis (NAA) of environmental and biological samples are presented. They are currently applied in the context of trace metal research related to the protection of the environment and human health. The radiochemical procedures are related to the separations of the elements into groups which allow the determination of up to 50 elements in each sample or to specific separations for single elements. The experience gained in the application of these radiochemical separations over more than ten years allows us to consider them as reliable for sensitive determinations of trace metals in environmental and biological samples.     

Some radiochemical separations employed at the Institute of Nuclear and Energy Research-Brazilian Nuclear Energy Commission

Several radiochemical separations have been employed at the Radiochemistry Division of the Institute of Nuclear and Energy Research-Brazilian Nuclear Energy Commision, for the analysis of a number of elements in different kinds of matrices. In the present paper some of these separations applied to the analysis of geological samples, geological and biological reference materials and Brazilian foodstuffs are described. The separation procedures utilized are mainly ion exchange, retention in inorganic exchangers like HAP, TDO and HMD and solvent extraction.     

Analytical radiochemistry of neutron activated samples in practice

Analytical radiochemistry of neutron-activated samples, as practiced during past decades at the Jo?ef Stefan Institute Ljubljana, is outlined. The paper reviews achievements made in both elemental analysis and analyses of long-lived radionuclides, in variety of sample types. The presented analytical procedures include application of diverse chemical separations, multiple irradiations of samples, use of various nuclear reactions and detection modes for particular measurands, and determination of elements that are difficult to be determined by neutron activation analysis (NAA). Useful practical applications of neutron-activated tracers for chemical yield determinations, as unique feature of radiochemical NAA in comparison with non-nuclear analytical methods, are also addressed.     

Group separation of rare earth elements by liquid-liquid extraction for the neutron activation analysis of silicate rocks

Rare earth elements are isolated as a group from neutron activated rock samples by a new radiochemical procedure based on extraction with thenoyltrifluoracetone/phenanthroline in CHCl₃. The procedure consists of three extraction steps, obviates the use of anactive carriers and gives practically quantitative chemical yields, thereby avoiding fractionation of the individual rare earths. Details of the dissolution, chemical separations and counting procedure are given togther with an analysis of BCR-1.     

Gas chemical methods for the separation of elements in radioisotope production and activation analysis

Summary Liquid-liquid extraction is used for one-atom-at-a-time separations of transactinide elements from heavy-ion reaction product mixtures. It is suitable for this purpose because it is fast, provided that a chemical system with negligible kinetics is used, and it can be used for continuous separations. It is, however, not quite easy to determine the uncertainties of the measured distribution coefficients or complex formation constants. In this paper methods for such estimates will be discussed.     

Characterization of copper chromate as a new inorganic exchanger for the isolation of Sr radioisotopes from fission products

A new inorganic exchanger consisting of the normal copper chromate (CUCR) was prepared and studied: its application to radiochemical separations was explored after batchwise measuring the distribution coefficients of several elements. Radiostrontium isolation from fission products was performed by combined use of CUCR and PRTD, a new form of tin dioxide previously investigated.     

气相色谱法在核化学与放射化学中的应用

在核化学与放射化学研究中,气相色谱法是一种非常重要的快速分离工具。它可以用于核反应产物的分离、核谱学研究,以及测定吸附焓,吸附熵,扩散系数等物化数据,研究超锕系元素的性质,探索其中的相对论性效应。本文主要介绍了在此领域中,气相色谱法的实验技术及应用,对其发展前景亦有所展望。     

Applications of silica-based monolithic HPLC columns

The recent invention and successive commercial introduction of monolithic silica columns has motivated many scientists from both academia and industry to study their use in HPLC. The first paper on monolithic silica columns appeared in 1996. Currently about 200 papers have been published relating to applications and characterization of monolithic silica columns, including monolithic capillaries. This review attempts to give an overview covering various aspects of this new column type in the field of high throughput analysis of drugs and metabolites, chiral separations, analysis of pollutants and food-relevant compounds, as well as in bioanalytical separations such as in proteomics. Some of the applications are described in greater detail. The numerous publications dealing with the physicochemical and chromatographic characterization of monolithic silica columns are briefly summarized.     

Some observations on the extraction of zinc with 3-methyl-1-phenyl-4-trifluoroacetyl-pyrazolin-5-one

Extraction of zinc with 3-methyl-1-phenyl-4-trifluoroacetyl-pyrazolin-5-one /FAP/ into chloroform has been investigated as a function of pH. The extraction is masked with cyanide and citrate ions. The extracted zinc can be quantitatively stripped into appropriate aqueous solutions. The distribution data of other metal ions show that zinc can be separated from a number of elements. Few possible applications of such separations from analytical and radiochemical point of view have been suggested.     

Nuclear activation methods for the characterization of fossil fuels

A review is presented on the use of neutron activation analysis (NAA) for the analyses of coal, oil shale, tar sands and petroleum. Fast NAA has been widely used for the determination of oxygen, and to a limited extent, of other elements such as nitrogen and silicon. Reactor NAA followed by instrumental counting, and in specific cases, after radiochemical separations is discussed. Thermal and epithermal neutrons are both used. Limited use of the²⁵²Cf source has been made in fuel analysis. A complementary technique to NAA is the photon-activation analysis with linear accelerator. It can determine over thirty elements, many of them not possible to do by NAA. Round-robin analyses of standard coal, fly ash, or oil shale samples indicate nuclear activation methods are comparable in accuracy and precision to X-ray fluorescence or atomic spectrometric methods for most elements.     

Miniaturized sample preparation combined with liquid phase separations

Miniaturized sample preparation methods designed as the sample pretreatment for liquid phase separations, such as liquid chromatography, capillary electrophoresis and capillary electrochromatography, have been reviewed especially for the on-line coupling of the sample preparation process and the separation process. The development of the desorption interfaces for the effective combining of the sample preparation and subsequent liquid phase separations is briefly described along with the applications of the combined analytical systems to the analysis of complex sample mixtures such as biological and environmental matrices. Novel use of fine polymeric filaments as the extraction medium for microscale liquid phase separation methods are investigated and a comparison is made with other sample preparation techniques. Polymer coating onto the fibrous material is also introduced to further develop microscale sample preparation methods with improved extraction performance. Several other microscale sample preparation methods having a potential compatibility to the liquid phase separations are also described for future applications of these techniques.     

Analytical problems related to the preparation of samples used in studies on metallobiochemistry of heavy metals pollution using neutron activation analysis

Severe analytical problems are associated with the analysis of heavy metals at very low levels in biological samples. This impose a high degree of sophistication of the NAA involving treatment of the sample before irradiation such as chemical separations, physical treatments and biochemical fractionation, the experimental evaluation of interfering nuclear reaction as well as the development of post-irradiation radiochemical separation. This paper treats of the problem related to the NAA of trace elements in environmental biochemical toxicology focussing attention of the sources of the elements during the analysis. Typical results and short discussion for every step of the analysis are reported.     

Separation techniques used in radiochemical procedures

After summarising the techniques available generally in analytical chemistry for the separation and pre-concentration of trace elements, reasons are given why some of these procedures have achieved greater prominence in particular radiochemical separations. Examples of contemporary practice and current trends in a wide variety of radiochemical separation problems are then illustrated by reference to papers that have appeared in recent literature. Adapted from a Plenary Lecture delivered at the 4th Symposium on Recent Developments in Neutron Activation Analysis, 4–7th August 1975, Cambridge, England.     

Determination of about thirty elements in aluminium and its alloys by means of neutron activation analysis

Neutron activation analysis and radiochemical separations in HCl, HF media are used to determine 30 elements in aluminium and alloys. Amounts lower than 1 μg of element may be determined. A good agreement is found with the results of atomic absorption spectrometry. This procedure is applied routinely for determinations of trace elements or major components.     

Use of reference materials for quality control of elemental analysis by neutron activation with radiochemical separation

Summary This paper describes the use of certified reference materials to monitor the long-term quality of radiochemical separations. The practical limitations which determine the actual design of the quality control are discussed. The hypothesis that the high yield of the radiochemical separation will be constant with time has been checked and validated for the elements Zn, Fe, Co, Cd, Mo and to a lesser extent for W and Th using NBS SRM 1577A, BCR CRM 274 and IAEA RM A-11. This validation could not be made for the elements Cr, Au and Ag. Especially for Cr there is a serious lack of appropriate certified reference materials.     

NAA characterization of the new Bovine Liver SRM

The National Institute of Standards and Technology (NIST) is preparing a freeze-dried powdered bovine liver tissue Standard Reference Material (SRM) to replace SRM 1577b Bovine Liver as the stock of this material was exhausted during 2006. Like the original SRM 1577 issued in 1972, this renewal focuses on the key elements for diagnostic, nutritional, and toxicological measurements that are important to medical, veterinary, and environmental sciences investigations. NIST’s approach for value assignment included extensive characterization by neutron activation analysis (NAA). Difficulties in the determination of some elements present at very low levels were overcome by use of radiochemical separations. Twentyone elements were characterized in SRM 1577c by NAA. The previous materials, SRM 1577 and 1577b, served as quality control.     

Radiochemical determination of trace noble metals in silver artefacts

Radiochemical separations are essential for the determination of trace elements in silver artefacts by neutron activation analysis due to the high levels of both short and long-lived activities produced by the matrix, but the sensitivity of the technique permits the examination of small samples. The noble metals are considered most significant from a diagnostic standpoint, and radiochemical techniques have been developed for their determination in samples of a few milligrams. Methods have been investigated for the determination of Pd, Rh, Ir and Pt in samples removed from museum specimens of known provenance.     

Rapid radiochemical separations using and induction furnace: Determination of sulphur in rocks

The use of an induction furnace for rapid radiochemical separations in neutron activation analysis of rocks is discussed in general and the activation analysis of sulphur in geological samples is described as a specific application. After irradiation the sample is heated in an induction furnace in a flow oxygen. The expelled sulphur oxides are adsorbed onto activated charcoal and measured in the well of a sodium iodide detector. The 3102 keV peak of the 5 minute³⁷S is used for analysis. The separation time is seven minutes, the yield 99% and the detection limit 200 μg S. Results of the analysis of ores are presented.     

Radiochemical separations by adsorption on some oxides of groups IVB and VB

The interactions between titanium dioxide, niobium pentoxide and tantalum pentoxide and 55 elements have been studied by batch experiments in nitric acid. The variation of the distribution ccefficients with nitric acid concentration is presented and discussed. The adsorption mechanism for some ions has also been investigated. Column experiments have been carried out to check the practical use of the investigated oxides in radiochemical separations. A^99mTc generator based on the use of TiO₂ is also presented.