Ellene Tratras Contis

Use of Nuclear Techniques for the Measurement of Trace Elements in Food

Considerable interest in determining levels of trace elements in foods has occurred in the last twenty years. This interest comes from studies attempting to determine the role that elements play in the flavor and in the toxicology of food. Radiochemical methods, like instrumental neutron activation analysis (INAA), are common techniques used to determine dietary trace levels of various elements. A summary of other methods are also referenced in this updated review of past, present, and future uses of radiochemical methods to determine trace elements in food.

Nutrition, functional and sensory properties of foods

The link between nutrition, food and health is well established and the global interest in these areas generates new information every day. This book pulls together the latest research on flavour chemistry and nutritional and functional properties of food. Topics covered in flavour chemistry begin with an overview of the analysis, occurrence and formation mechanism of furan, a food-borne carcinogen, then focuses on analysis of melamine, the uses of enzymes to modify flavours of wines and protein as a process flavour precursor and finally includes information on the volatile compounds in an array of food products and ingredients such as coriander, chamomile, saffron and dry fermented sausage. Coverage in the nutritional and functional properties of food section is wide range and includes reviews of the hot topics such as the metabolism of dietary phenolic acids, the use of emulsions for the oral delivery of bioactive phytochemicals and the impact on epigenetics in cancer prevention. Written by international experts in the field and edited to a high standard, this title will provide a unique reference for researchers and other professionals in the industry and academia, particularly those directly involved in food science.

Chemical reactions of fission products with ethylene using the gas jet technique

Abstract An understanding of the nature of the chemical reactions taking place between fission products and their carrier gases, and the designing of a fast separation procedure were the purposes of this investigation. Chemical reactions of short-lived (less than one minute half-life) fission products with carrier gases lead to various chemical species which can be separated in the gas phase. The Gas Jet Facility at the Ford Nuclear Reactor was used to study the yields of volatile selenium and bromine fission products of 235 U using a semi-automatic batch solvent extraction technique. Heptane and water were used as organic and inorganic solvents. A carrier gas mixture of ethylene to pre-purified nitrogen (1:3) was used to sweep the fission products from the target to the chemistry area for analysis. The results indicated that the volatile selenium products generated by the interaction of selenium fission fragments with ethylene were predominantly organic in nature (84%), possibly organoselenides. The selenium values were used to resolve the fractions of the bromine nuclides, which come from two major sources, viz., directly from fission and from the beta-decay of selenium. The data showed that the fractions of independent bromine fission products in the organic phase were much lower compared to selenium; the bromine values range from 10 to 22% and varied with mass number. Results indicated that the bromine products were inorganic in nature, as possibly hydrogen chloride.

EVOLUTION AND APPLICATIONS OF RADIOCHEMICAL PROCEDURES : FROM MARIE CURIE TO DARLEANE HOFFMAN

Marie Curie carried out the first radiochemical separations which eventually lead to the discovery of polonium and radium, two new elements. Nearly a century later Darleane Hoffman and her collaborators are devising new radiochemical separation procedures for studying the chemical properties of newly discovered transactinide elements. Safety requirements as well as changes necessitated by fast decaying radionuclides have transformed the nature of radiochemical separations. Further, applications in a wide variety of areas such as analysis of trace lements in food to radioimmunoassay have broadened the use of radiochemical separations. Examples of some early, historically important, radiochemical separations are described in this article. In addition, recent trends in the use of radiochemical separations in neutron activation analysis. in dating applications. in fission product studies and in the study of transactinide elements are briefly described with specific examples.

Gas phase chemical reactions of fission products with ethylene using the gas jet technique

Gamma-ray spectroscopy can be used to identify short-lived fission products in chemical fractions obtained by gas phase transport and liquid–liquid extraction. Volatile compounds of selenium and bromine fission products of 235U were studied using a semi-automatic batch solvent extraction technique. The resulting gamma-ray spectra of the heptane and water phases were consistent with the nuclides of interest (84Se, 85Se, 86Se and 86Br, 87Br, 88Br), activation products, and neutron reactions with the Ge in the detectors. The procedure used to identify these peaks is reported.

Analysis of drinking water near and far from thermal springs using instrumental neutron activation analysis

Abstract This project investigated what effect, if any, there was on drinking water near and far from radioactive thermal springs. The focus was to analyze several drinking water samples for trace elements, especially those of nutritional and toxic value. Elements of interest included selenium (Se), vanadium (V), arsenic (As), mercury (Hg), cadmium (Cd). Samples from nine different springs were collected from an island in the eastern Aegean Sea in Greece, Ikaria, which is known for its radioactive therapeutic baths. The liquid samples were irradiated and counted after 3 days and 15 days using the instrumental neutron activation analysis technique. Analysis of the samples revealed typical elements found in natural water: sodium (Na), bromine (Br), potassium (K). In addition, some of the samples indicated ultra traces of uranium (U). These amounts, were attributed to natural radiation found in typical geological formations. Results indicated that there were no statistically significant traces of the elements of interest in the water samples.

Transport time of volatile and nonvolatile fission products in a gas jet

Abstract Transport times for volatile and nonvolatile fission products in a gas jet were determined using the facility at the Ford Nuclear Reactor of the University of Michigan. A mixture of ethylene and nitrogen was used to sweep the fission products from the target chamber in the gas jet. Activated charcoal traps [C] and quartz wool traps [QW] were used to collect the volatile and nonvolatile fission products respectively. The trap was positioned in front of a HPGe detector. A “stopped-flow” technique was used for the transport time measurement. The gas flow was controlled with electrically operated valves; the application of power to the valves also triggered the counting in multiscaler mode. Measurements were carried out for two target pressures. For each pressure a number of measurements were done with the charcoal and the quartz wool traps. For a target pressure of 4 psi above atmosphere transport times of 432 ± 41 and 432 ± 23 ms were obtained for the volatile [C] and nonvolatile [QW] fission products respectively; at about atmospheric pressure the corresponding values were 458 ± 33 and 443 ± 38 ms. The values indicated that there is no significant difference in the transport time for the volatile and nonvolatile fission products in a gas jet.