Determination of chromium in biological materials by radiochemical neutron activation analysis (RNAA) using manganese dioxide.

A procedure based on radiochemical neutron activation analysis was developed for the determination of chromium in biological materials. The procedure consists of irradiation of reference and test samples in a nuclear reactor, microwave sample digestion, selective and quantitative radiochemical separations of chromium and gamma-ray spectrometric measurement of 51Cr. Separation of chromium from the accompanying elements was done on the column packed with inorganic resin MnO2 Resin. Distribution coefficients of Cr, Zn, Co, Cs and Sc were determined in the system: MnO2 Resin-HCl, HNO3 and H2SO4. Accuracy of the procedure was checked by analysis of certified reference materials.

Determination of hafnium at the 10(-4)% level (relative to zirconium content) using neutron activation analysis, inductively coupled plasma mass spectrometry and inductively coupled plasma atomic emission spectrometry.

Hafnium at the very low level of 1-8 ppm (in relation to zirconium) was determined in zirconium sulfate solutions (originating from investigations of the separation of ca. 44 ppm Hf from zirconium by means of the ion exchange method) by using three independent methods: inductively coupled plasma mass spectrometry (ICP MS), neutron activation analysis (NAA) and inductively coupled plasma atomic emission spectrometry (ICP-AES). The results of NAA and ICP MS determinations were consistent with each other across the entire investigated range (the RSD of both methods did not exceed 38%). The results of ICP-AES determination were more diverse, particularly at less than 5 ppm Hf (RSD was significantly higher: 29-253%). The ion exchange method exploiting Diphonix(®) resin proved sufficient efficiency in Zr-Hf separation when the initial concentration ratio of the elements ([Zr]0/[Hf]0) ranged from 1200 to ca. 143,000.

Inductively coupled plasma mass spectrometry in comparison with neutron activation and ion chromatography with UV/VIS detection for the determination of lanthanides in plant materials.

Analytical performance of inductively coupled plasma mass spectrometry (ICP-MS) for determination of lanthanides in plant materials was investigated and compared with neutron activation analysis (NAA) as well as ion chromatography (IC) with UV-VIS detection. Two sample preparation protocols were tested: (i) microwave assisted digestion by concentrated nitric acid; (ii) microwave digestion involving silica and fluoride removal, followed by the selective and quantitative lanthanides group separation from the plant matrix. Several Certified Reference Materials (CRM) of plant origin were used for the evaluation of the accuracy of the applied analytical procedures. The consistency of results, obtained by various methods, enabled to establish the tentative recommended values (TRV) for several missing elements in one of CRMs. The ICP-MS, due to its very high sensitivity, has the potential to contribute to this aim. The discrepancy of the results obtained by various methods was discussed in a view of possible matrix effects related to the composition of investigated materials.

Two new reference materials based on tobacco leaves: certification for over a dozen of toxic and essential elements.

The preparation, certification, and characterization of two new biological certified reference materials for inorganic trace analysis have been presented. They are based on two different varieties of tobacco leaves, namely, Oriental Basma Tobacco Leaves (INCT-OBTL-5), grown in Greece, and Polish Virginia Tobacco Leaves (INCT-PVTL-6), grown in Poland. Certification of the materials was based on the statistical evaluation of results obtained in a worldwide interlaboratory comparison, in which 87 laboratories from 18 countries participated, providing 2568 laboratory averages on nearly 80 elements. It was possible to establish the certified values of concentration for many elements in the new materials, that is, 37 in INCT-OBTL-5 and 36 in INCT-PVTL-6, including several toxic ones like As, Cd, Hg, Pb, and so forth. The share and the role of instrumental analytical techniques used in the process of certification of the new CRMs are discussed.

Myocardial iron homeostasis in advanced chronic heart failure patients.

BACKGROUND: Although, correction of iron deficiency and/or anemia in heart failure (HF) with iron seems promising, little is known about myocardial iron load and homeostasis. Moreover iron supplementation indications are solely based on iron serum markers. The purpose was to assess myocardial iron (M-Iron), ferritin (M-FR), transferrin receptor (M-sTfR) in HF in relation to serum Iron markers. METHODS AND RESULTS: Study group 33 patients, left/right ventricle (LV/RV) (LVEDV 245 ± 84 ml; LVESV 189 ± 85 ml; LVEF 22 ± 11%; RVD 32 ± 10 mm), NTproBNP (5464 ± 4825 pg/ml). Iron homeostasis assessment serum: iron, FR, transferrin/saturation (TSAT), sTfR; myocardial: M-Iron (Instrumental Neutron Activation Analysis, µg/g), M-FR, M-sTfR (ELISA - ng/mg protein) in the explanted failing hearts (FH), compared to non-failing hearts (NFH n=11). In FH as compared to NFH, M-Iron was reduced in RV (174 ± 45 vs 233 ± 97, respectively, p=0.07), LV (189 ± 58 vs 265 ± 119, p=0.04), without significant changes in M-FR/M-sTfR. Out of all serum iron markers only sTfR was negatively correlated with M-Iron in either ventricle (RV r=-0.44, p=0.03, LV r=-0.38, p=0.07). With regard to serum iron status, based on TSAT, patients were divided into two subgroups: reduced (TSAT<15%; n=11) and not-reduced serum iron (TSAT ≥ 15%; n=22). Both subgroups had similar grade of LV/RV dysfunction, NT-proBNP levels. M-FR was lower in TSAT<15% than in TSAT ≥ 15% (LV -31 ± 26 vs 46 ± 29; p=0.07) and (RV -24 ± 24 vs 43 ± 29; p=0.02), without differences in M-Iron and M-sTfR. CONCLUSIONS: In HF, M-Iron levels were reduced. Serum iron markers did not reflect M-Iron levels, except for serum sTfR. In reduced serum iron group, decrease in myocardial storage protein M-FR was observed.

Comparison of performance of INAA, RNAA and ion chromatography for the determination of individual lanthanides.

Lanthanides represent an interesting group of elements which are steadily gaining importance in science and in industry. Literature data suggest that they may have a role in regulating cellular processes and also in agriculture enhancing plant growth. Only few instrumental methods like NAA, ICP-OES and ICP-MS have potential for the determination of low levels of all lanthanides, but in practice they often have to be combined with suitable separation/preconcentration methods to achieve maximum number of elements being determined and to assure good accuracy and precision. In this work an attempt has been made to compare the performance of both variants of NAA: purely instrumental activation analysis (INAA) and radiochemical mode (RNAA) with pre- and post-irradiation group separation for the determination of individual lanthanides with the special emphasis on rarely determined elements (Gd, Ho, Er, Tm, Lu). This has been done by the analysis of two reference materials with different matrices viz. biological (CTA-OTL-1) and mineral (CTA-FFA-1). The results are compared with those obtained by ion chromatography (IC) employing the same lanthanide group preseparation scheme as in the case of RNAA.

RNAA in metrology: A highly accurate (definitive) method.

The idea of highly accurate (definitive) methods by radiochemical neutron activation analysis (RNAA) is presented and illustrated with several examples of methods worked out in this Laboratory over the past several years. Definitive methods by RNAA are constructed by combining reactor neutron activation with very selective and quantitative post-irradiation separation of the indicator radionuclide by column chromatography followed by gamma-ray spectrometric measurement. All conditions for the determination of the individual element are optimized and uncertainties associated with every step of the analytical procedure are minimized. Even after the method has been thoroughly elaborated and validated through the analysis of appropriate certified reference materials (CRMs), the results obtained in each series of measurements are acknowledged as obtained by definitive method only when a series of previously formulated criteria is simultaneously fulfilled. The examples of definitive methods for the determination of cadmium, cobalt and molybdenum, respectively, in biological materials are presented. Each of these methods has detection limit of the order of ng g(-1) or better, and yields accurate and precise results. The expanded standard uncertainty is of the order of 2.6% for the case of single-element determination (Co) and 3.4-5.2% for the less favourable case (Mo) where there is necessity for simultaneous determination of uranium to correct for interference due to fission reaction. Definitive methods by RNAA may constitute an option or alternative with respect to ID-MS as methods of "guaranteed accuracy" being also a perspective solution in the case of monoisotopic elements, for which ID-MS cannot be used.