M. Dermelj

Some trace elements in the waters, marine organisms and sediments of the Adriatic by neutron activation analysis

A number of investigations of trace elements in the waters, organisms and sediments of the Adriatic, using neutron activation analysis with radiochemical, separations are reported. These include studies of Hg in mussels from the Northern Adriatic, of Hg and Se in edible animals from the Rijeka region, and of seven elements (As, Cd, Cu, Hg, Mn, Se and Zn) in marine invertebrates from the Slovene coast. Additionally, plankton, sediment cores and water samples were taken from a grid of stations covering the whole Adriatic and analyzed for 6 to 11 of the trace elements As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Sb and Zn (Hg only in water). Generally, levels found were not indicative of pollution as compared with oceanic samples, but some evidence of locally increased levels was found, especially for Hg. The levels of eleven trace elements in three marine Intercomparison samples prepared by the IAEA Monaco Laboratory are also presented.

Iodine in different food articles and standard reference materials

SummaryThe greater part of essential iodine enters living organisms via the food chain. Nevertheless, quantitative data on its concentration in diets, food articles and also in available SRMs are very poor and scarce. This and WHO recommendations on daily allowances of iodine for man via food articles caused an added demand for accurate and reliable determination of iodine in these samples. From this point of view the purpose of the present was to analyse and to establish the concentration levels of total iodine in some food articles, diets, SRMs and candidate reference materials by the use of rapid radiochemical separation, developed in our laboratory. The results were checked by the analysis of SRMs with available certified values for iodine and good agreement is evident.

Determination of trace elements in tobacco using different techniques of neutron activation analysis

Quantitative data on trace elements in two tobacco leaf (candidate) reference materials OTL-1 and VTL-2 prepared by the Polish Academy of Sciences and the Institute of Nuclear Chemistry and Technology, Warsaw, Poland, are presented and compard to recommended values, where available. By instrumental neutron activation analysis (INAA), as well as by radiochemical technique (RNAA) 30 elements were quantitatively determined and fair agreement was found between the results and recommended values for the first material.

Simultaneous determination of iodine and selenium in biological samples by radiochemical neutron activation analysis

SummaryRegarding the favourably sensitive nuclear characteristics of iodine and of selenium but the very different half lives of their induced nuclides 128I and 75Se, a radiochemical neutron activation analysis method for simultaneous determination of these elements in a single sample was developed. It is based on the double irradiation LICSIR technique — Long Irradiation for Se (40h), Cooling (a week or more), Short Irradiation for iodine (1–15 min) with following Radiochemistry. After the second short irradiation, the sample is ignited in an oxygen flask and iodine and selenium are sequentially and selectively extracted as elemental iodine and 5-nitro-2,1,3 benzoselena diazole chelate. With the described method biological samples were analysed and the reliability of the results was checked by the analyses of different standard reference materials. Good agreement with certified values and high radiochemical purity of the spectra show the applicability of the radiochemical separation developed.

Trace heavy metals in various Yugoslav tobaccos

SummaryLevels of trace heavy metals in various kinds of tobacco are poorly studied, so their determination in this matrix is important both from the point of view of health studies connected with smoking and more general aspects of the uptake of trace elements by plants. Because of its great sensitivity, neutron-activation analysis is very suitable for determination of trace heavy metals. The great range of concentrations to be expected makes non-destructive analysis less suitable. Thus As, Cd, Cu, Hg, Mn, Sb, Se, U, V and Zn were determined by means of rapid radiochemical separations and measurement of theγ-ray spectra of the isolated radionuclides with an NaI detector. Iron, and manganese at higher levels, was determined spectrophotometrically. The accuracy of the results, which represent the mean value of at least two measurements for about 10 varieties of Yugoslav tobacco, was checked by the analysis of various standard reference materials and good agreement were obtained with certified or literature values. The results were compared with analyses of Kentucky IR-1 tobacco.ZusammenfassungDie Schwermetallspuren in verschiedenen Tabaksorten wurden bisher nur wenig untersucht. Deren Bestimmung ist sowohl für Fragen der Gesundheit der Raucher wie im allgemeinen hinsichtlich der Spurenelementaufnahme durch Pflanzen von Bedeutung. Die Neutronenaktivierungsanalyse ist für die Bestimmung von Schwermetallspuren ihrer hohen Empfindlichkeit wegen sehr geeignet. Die weiten Konzentrationsgrenzen, mit denen zu rechnen ist, lassen nicht-destruktive Analysenverfahren weniger geeignet erscheinen. Daher wurden As, Cd, Cu, Hg, Mn, Sb, Se, U, V und Zn radiochemisch rasch abgetrennt und die Gammaspektren der isolierten Radionuklide mit einem NaJ-Detektor bestimmt. Größere Mengen Eisen und Mangan wurden spektrophotometrisch bestimmt. Die Genauigkeit der Ergebnisse, die ihrerseits den Durchschnittswert von wenigstens zwei Messungen bei ungefähr 10 jugoslawischen Tabaksorten darstellen, wurde durch Vergleich mit verschiedenen Standardproben geprüft. Dabei wurde gute Übereinstimmung mit gesicherten Werten bzw. Literaturangaben erzielt. Die Resultate wurden mit Analysenwerten von Kentucky-IR-1-Tabak verglichen.

Applicability of neutron activation analysis (NAA) in quantitative determination of some essential and toxic trace elements in food articles

Accurate and reliable data on microgram and nanogram quantities of some essential and toxic elements in most food articles are very scarce. Neutron activation analysis (NAA), with its essentially blankfree advantage, is a valuable approach in the field of determination of trace elements in different foodstuffs and diets. Accordingly, various radiochemical (RNAA) and instrumental (INAA) approaches have been developed in our laboratory for the elements As, Cd, Co, Cu, Hg, I, Mo, Ni, Sb, Se, Sn, Th, U, V, and others, and verified by the analysis of compositionally appropriate certified reference materials.

The use of 4-nitro-o-phenylene diamine /4-NDP/ and sodium diethyldithiocarbamate /Na-DDTC/ in the radiochemical separation of Cd, Co, Cu, Se and Zn from different biological samples

In this work the use of the reagents 4-NDP and Na-DDTC in the radiochemical separation of Cd, Co, Cu, Se and Zn from a single aliquot of sample shortly after the end of irradiation in a flux of thermal neutrons is described. The performance of the proposed separation method was tested by means of analyses of these elements in a series of SRMs and good agreement with certified values was obtained.

Radiochemical neutron activation analysis in standardization of trace elements in biological reference materials at the nanogram level

SummaryResults for up to 12 trace elements in some newer biological materials of the NBS Washington (Citrus Leaves, New Bovine Liver, Wheat and Rice Flours, Milk Powder, Stabilized Wine) are reported using radiochemical neutron activation analysis. A discussion of the techniques and problems of standardization and the correct use of standards is included.ZusammenfassungErgebnisse für bis zu 12 Spurenelemente in einigen neuen biologischen Proben des NBS, Washington, (Citrus-Laub, frische Rindsleber, Weizenund Reismehl, Milchpulver, Wein) wurden mitgeteilt, die mittels radiochemischer Neutronen-Aktivierungs-Analyse erhalten wurden. Eine Diskussion der Verfahren, der Probleme der Standardisierung sowie der korrekten Verwendung der Standardproben wurde geboten.

Determination of selenium in biological materials by means of RNAA and comparison of spectrophotometric and81mSe radiotracer recovery

Two methods for chemical yield measurement of Se in biological samples after radiochemical neutron activation analysis when using the75Se nuclide are described, namely a Spectrophotometric technique and a radiotracer technique employing81mSe. These two approaches were compared and evaluated by applying them to the analysis of Se in various certified reference materials.

Determination of trace amounts of selenium in poultry feedstuffs by gas chromatography

In view of the importance of establishing reliable selenium concentration levels in different kinds of feedstuffs, the purpose of this work was to develop optimum experimental conditions for the isolation and GC determination of selenium as its chelate with 4-nitro-1,2-diaminobenzene. It was shown that ignition of the sample in an oxygen flask followed by reduction of Se(VI) to Se(IV) and the formation of 5-nitro-2,1,3-benzoselenadiazole chelate in HCl medium is a relatively rapid procedure giving a low blank value and allowing the determination of selenium in commercial feedstuffs and similar biological samples. The method was validated by the analysis of suitable certified or standard reference materials.