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Abstract. Retention of selected analytes (Cd, Cr, Cu, Mn, Pb, Zn) in solid residue which remains undissolved in 1.5% HNO 3 used as a leaching medium after classical dry ashing of ten materials (alfalfa leaves, NIST SRM 1569 Brewer's Yeast, blood meal, meat-bone meal, feather-bone meal, silage residue, litter, pond sediment, coal waste, IRM NSC-21 Industrial Compost Vitahum) was studied . The elements remaining in the residue were determined mainly by AAS after dissolution of this residue in the mixture of HF + HNO 3 . In several instances, pressurized wet digestion, alkaline fusion, stripping voltammetry and instrumental neutron activation were also applied. Increasing concentration of mineral acid in leaching medium which does not contain HF, plus increasing final volume of the solution, suppresses significantly this type of analyte losses in the majority of matrices tested. However, for industrial compost and standard reference material NIST 1569 Brewer's Yeast, application of an HF step is necessary for quantitative release of the analytes (in particular chromium) into solution.Key words. Biological and agricultural materials -dry ashing -trace element analysis -analyte losses.

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Wheat is worldwide consumed and contributes significantly to the intake of antioxidants with beneficial healthy effects. In the precise two-year field experiments in 2008 and 2009 two varieties of wheat einkorn, two varieties of emmer wheat and three varieties of spring wheat and in 2009 in addition two other spring wheat varieties, three einkorn varieties and three emmer wheat varieties were evaluated for selenium content and antioxidants -total polyphenols (TP). Selenium content was determined by atomic absorption spectrometry with hydride generation technique (HGAAS) and total polyphenols with Folin-Ciocalteau assay. Higher selenium content in grain is related to emmer (58.9-68.4 µg/kg DM) and einkorn (50.0-54.8 µg/kg DM) varieties; in spring varieties selenium content ranged from 29.8 to 39.9 µg/kg DM. Among the varieties with high TP (expressed in gallic acid equivalents) emmer varieties prevail (584-692 mg/kg DM), less represented are einkorn (507-612 mg/kg DM) and spring wheat (502-601 mg/kg DM) varieties. Among varieties significant differences were determined. TP were significantly higher in emmer wheat varieties and one einkorn and one spring wheat variety. Between TP and Se significant linear correlation was determined (r = 0.709).

Bioaccumulation of cadmium, chromium, copper, manganese, nickel, lead, and zinc in 56 foxes (Vulpes vulpes) and their parasites Mesocestoides spp. (Cestoda) and Toxascaris leonina (Nematoda) was studied. The levels of heavy metals were determined in the livers and kidneys of the animals depending on parasitism in the following ranges: Pb, 0.029-3.556; Cd, 0.055-9.967; Cr, 0.001-0.304; Cu, 4.15-41.15; Mn, 1.81-19.94; Ni: 0.037-0.831; Zn, 52.0-212.9 microg/g dry weight (dw). Cd in parasites (0.038-3.678 microg/g dw) were comparable with those in the livers of the host and lower than in the kidneys (0.095-6.032 microg/g dw). Contents of Pb, Cr, Cu, Mn, Ni, and Zn in cestodes were predominantly higher than those in the kidney and liver of the host. Median lead levels in Mesocestoides spp. (45.6 microg/g dw) were 52-fold higher than in the kidney and liver of the red fox (Vulpes vulpes) infected by both parasites and median Pb values in T. leonina (8.98 microg/g dw) were 8-fold higher than in the tissues of the parasitized red fox. Bioaccumulation factors of copper, zinc, nickel, and manganese are lower than those of lead and mostly range from 1.9 to 24 for Mesocestoides spp. and from 1.5 to 6 for nematode T. leonina depending on the tissue of host and element. A significant decrease in the content of Pb was found in the kidney of animals infected by T. leonina (0.260 microg/g dw) as well as those infected by Mesocestoides spp. (0.457 microg/g dw) in comparison with the lead content (0.878 microg/g dw) in the kidneys of the nonparasitized red fox. Regardless of a bioaccumulation of copper and manganese in the parasites, a significant increase of the concentrations of Mn and Cu was observed in the host's livers infected predominantly by Mesocestoides spp.