L. Kosta

Vanadium in foods and in human body fluids and tissues

Using neutron activation analysis, vanadium was analysed in a range of foods, human body fluids and tissues. On the basis of these results and those of other workers, it was concluded that daily dietary intake amounts to some tens of micrograms. Analysis of body fluids (including milk, blood and excreta) and organs and tissues provided an estimate for the total body pool of vanadium in man of about 100 microgram. Vanadium was not detectable in blood and urine at the level of 0.3 ng/g, while low levels were found in muscle, fat, bone, teeth and other tissues. The relationship between dietary intake to pulmonary absorption is discussed in relation to the occurrence of vanadium in man-made air particulates. The very low levels found in milks and eggs suggest minimal vanadium requirements in growth. The findings are discussed in the light of previous results and also in relation to the possible essentiality of vanadium.

Trace element concentrations in higher fungi.

The concentrations of ten trace elements, As. Br, Cd, Cu, Hg I, Mn, Se, Zn and V, have been determined in up to 27 species of higher fungi from several sites in Slovenia, Yugoslavia. Analyses were based on destructive neutron activation techniques. Data are presented and compared with the concentrations found in soils. Previously values were non-existent or scanty for these elements, so that the data represent typical levels for basidiomycetes. In addition to confirming high levels of mercury in many species, the survey also found that cadmium is accumulated to a surprising extent by most fungi, the average value being 5 ppm. Among other accumulations found was bromine by the genus Amanita, and selenium by the edible Boletus. Correlation analysis between all pairs of trace elements gave values for r of from 0.75 to 0.43 for 7 pairs (Cu and Hg, 0.75; Se and As, 0.69). As well as these features of biochemical interest, the values found and the pattern of accumulation suggest potential uses of fungi in environmental studies.

ACTIVATION ANALYSIS FOR MERCURY IN BIOLOGICAL SAMPLES AT NANOGRAM LEVEL.

A new method has been devised for determining mercury in samples of biological origin. It is based on complete ignition of the sample in a silica tube, trapping volatile interfering activities such as bromine or chlorine, and selectively adsorbing mercury on a strip of filter paper which has been previously impregnated with elemental selenium. This strip is later counted for quantitative evaluation. The versatility of the method has been demonstrated by the analysis of a wide range of samples such as water, cellulose, flour, fish solubles or animal blood samples with mercury contents between 1 and 200 ng g of sample.

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.

A new method for the isolation of methylmercury from biological tissues and its determination at the parts-per-milliard level by gas chromatography

A new method has been developed for the isolation of methylmercury from biological tissue. It is based on the volatilization of methylmercury cyanide formed in the reaction of methylmercury in the tissue with hydrocyanic acid released in the interaction of potassium hexacyanoferrate(II) with sulphuric acid at elevated temperature. The methylmercury cyanide released is captured on cysteine paper in a microdiffusion cell. The isolated methylmercury is set free with hydrochloric acid, extracted into benzene and determined by gas chromatography. A special closed micro-extractor is used for the final extraction into benzene for samples containing the lowest levels of methylmercury. The method can be used for a wide range of samples and concentrations (including background levels). The simplicity of the method makes it suitable for routine application.

Trace elements in some human milk samples by radiochemical neutron activation analysis

Some trace element contents of samples of human milk, mainly colostrum and transitional milk, collected in the Ljubljana area of Yugoslavia, are reported. Analyses of As, Cd, Co, Cu, Hg, I, Mn, Sb, Se, Sn, V and Zn were performed by radiochemical neutron activation analysis, and the results are discussed briefly in the light of literature values.

Amperometric determination of cyanide by use of a flow-through electrode☆

A new approach to cyanide determination based on the measurement of the diffusion current arising from the oxidation of silver to dicyanoargentate(I) is described. Parameters defining the effect of the electrode geometry and the hydrodynamic characteristics of the system on the response of the electrode have been evaluated so that the performance can be optimized. Response is fast and linear for levels from one microgram to several grams per litre of solution. By use of the flow injection principle and a manifold arrangement, absolute amounts of less than one nanogram of cyanide can be determined precisely in volumes as small as 10 mul and at a rate exceeding 100 samples per hour. The method is easily adapted to automated routine analytical control and continuous monitoring of industrial processes depending on the use of cyanide, such as galvanizing plants and certain organic synthetic industries, and also to control of effluents.

Determination of vanadium in biological materials at nanogram level by neutron activation analysis

A method for the destructive activation analysis of vanadium in biological samples at the nanogram level has been developed, based on 3.75 min52V. A totally post-irradiation procedure is used, consisting of wet ashing and solvent extraction with N-benzoyl-N-phenylhydroxylamine (BPHA). Time of separation is about 12 min and the radiochemical purity excellent. Possible nuclear interferences were also investigated. The procedure was checked by an alternative method, using preashing and pyrosulfate fusion, and at higher levels, by nondestructive analyses. Results are presented for some 15 standard (or proposed) standard reference materials.

On the vanadium and tin contents of diet and human blood

The vanadium and tin contents of total diet samples collected in five Italian towns are given, and discussed in relation to literature data, their status as essential elements and their levels in human blood. Tin in blood was found to be below 2 ng ml-1 in a group of 14 subjects, and barely detectable even after oral consumption of 60 mg of tin.

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.