Urska Repinc - Academia.edu (original) (raw)
Papers by Urska Repinc
Journal of Radioanalytical and Nuclear Chemistry, 2016
In the frame of the accountancy measurements of the fissile materials, reliable determinations of... more In the frame of the accountancy measurements of the fissile materials, reliable determinations of the plutonium and uranium content in spent nuclear fuel are required to comply with international safeguards agreements. Large-sized dried (LSD) spikes of enriched 235 U and 239 Pu for isotope dilution mass spectrometry (IDMS) analysis are routinely applied in reprocessing plants for this purpose. A correct characterisation of these elements is a pre-requirement for achieving high accuracy in IDMS analyses. This paper will present the results of external verification measurements of such LSD spikes performed by the European Commission and the International Atomic Energy Agency.
International Journal of Mass Spectrometry, 2014
Environmental Radiochemical Analysis II
Journal de Physique IV (Proceedings), 2003
The routine determination of the activity concentrations of uranium isotopes (mU, mU and 234U), t... more The routine determination of the activity concentrations of uranium isotopes (mU, mU and 234U), thorium isotopes (212Th, 230TI, and 228Th), 23'Pa, 22'Ra, 210Pb and 210pro in the environment is one of the most important tasks in uranium mining areas. Natural radionuclides contribute negligibly to the extemal radiation dose, but in the case of ingestion or inhalation can represent a very serious hazard. The objective of this study was to determine the activities of uranium and its decay products 230Th, 231Pa, 226Ra, 210Pb alld 210po in sediments and water below sources of contamination (uranium mine, disposal sites and individual inflows) using gamma and alpha spectrometry, beta counting, me liquid scintillation technique and radiochemical neutron activation analysis.
Applied Radiation and Isotopes, 2010
Radium-226 is one of the best known long-lived a-emitters abundantly present in the environment. ... more Radium-226 is one of the best known long-lived a-emitters abundantly present in the environment. The determination of radium isotopes in environmental samples usually requires a demanding chemical separation before measurement and quantification. Each step in the chemical separation process can involve losses of the analyte, therefore it is of vital importance that the recovery of the whole radiochemical procedure is evaluated. The emphasis of the work presented was determination of the chemical recovery using the different yield tracers Ra-223, Ra-225 and Ba-133.
Accreditation and Quality Assurance, 2011
Calcium is an important constituent of mineral like calcite, dolomite, gypsum and bio-ceramic raw... more Calcium is an important constituent of mineral like calcite, dolomite, gypsum and bio-ceramic raw material like hydroxyapatite. Those are frequently used for the manufacture of cement, mortar, glass, synthetic ceramic bone supplement, dental enamel, etc. Determination of exact quantity of calcium in those materials is therefore very essential. The calcium content has been determined complexometrically in a ceramic raw material at pH 12, using di-sodium salt of EDTA. The major sources of uncertainty of the results of measurement are contributions from repeatability, standardization of EDTA, volume measurement by volumetric flask, burette, pipette and end point detection. Sources of uncertainty have been identified and combined by following the EURACHEM guidelines. The results show that the major sources of uncertainty arise from standardization, repeatability of the experiment and end point detection by burette. Cause-effect diagram has been drawn to explain the uncertainty budget.
Uranium in the Aquatic Environment, 2002
The uranium mine and mill at Žirovski vrh (RŽV), Slovenia stopped mining and milling in 1990. Mil... more The uranium mine and mill at Žirovski vrh (RŽV), Slovenia stopped mining and milling in 1990. Mill tailings containing about 20 % moisture were transported to a disposal site called Boršt. The objective of this work was to study the migration of the radionuclides U-238, Ra-226, Pb-210 and Po-210 from the Boršt waste disposal site. For determination of radionuclides, gamma and alpha spectrometry, beta counting, neutron activation analysis and liquid scintillation techniques were used.
Radiochemical neutron activation analysis (RNAA) is an excellent method for determining uranium a... more Radiochemical neutron activation analysis (RNAA) is an excellent method for determining uranium and thorium; it offers unique possibilities for their ultratrace analysis using selective radiochemical separations. Regarding the favourably sensitive nuclear characteristics of uranium and of thorium with respect to RNAA, but the different half-lives of their induced nuclides, two different approaches were used. In the first approach uranium and thorium were determined separately via U, Np and Pa. In the second approach these elements were determined simultaneously in a single sample using U and/or Np and Pa. Isolation of induced nuclides was based on separation by extraction and/or anion exchange chromatography. Chemical yields were measured in each sample aliquot using added U, Np and Pa radioisotopic tracers.
Examples on traceability, measurement uncertainty and validation for measurements of retinol and ... more Examples on traceability, measurement uncertainty and validation for measurements of retinol and α‐tocopherol in human serum, cyclamate in soft drinks, arsenic in groundwater, sodium chloride in milk products and total organic carbon in waste water are presented in this book. Additionally, the idea and structure of the TrainMiC® examples, which complement the TrainMiC® theoretical presentations, are described in detail to give a complete overview of the TrainMiC® teaching material. HOW TO OBTAIN EU PUBLICATIONS Free publications: • via EU Bookshop (http://bookshop.europa.eu); • at the European Union’s representations or delegations. You can obtain their contact details on the Internet (http://ec.europa.eu) or by sending a fax to +352 2929-42758. Priced publications: • via EU Bookshop (http://bookshop.europa.eu). Priced subscriptions (e.g. annual series of the Official Journal of the European Union and reports of cases before the Court of Justice of the European Union): • via one of ...
... The background values, because of the lack of shielding, were quite high (~35 cpm, 226Ra win... more ... The background values, because of the lack of shielding, were quite high (~35 cpm, 226Ra window). * E-mail: urska.repinc@ijs.si 02365731/2002/USD 17.00 ... Meth., 165 (1975) 345. 1. I. KOBAL, M. SHAHIN, J. KRISTAN, M. SENEGAC ∨ NIK, Health Phys., 27 (1974) 381. ...
Journal of Radioanalytical and Nuclear Chemistry Articles, 1995
A method for the simultaneous, radiochemical neutron activation analysis of uranium and thorium a... more A method for the simultaneous, radiochemical neutron activation analysis of uranium and thorium at trace levels in biological materials is described, based on a technique known as LICSIR, in which a 23 double neutron irradiation is employed. In the first, long irradiation '"Pa (27.0 d) is induced by neutron capture on 232Th and then the sample is cooled for several weeks. A second short irradiation to induce 23~' 23 U (23.5 m) is followed by a rapid sequential radiochemical separation by solvent extraction of 9U with TBP and 233pa with TOPO. Chemical yields of 239U and 233pa were measured for each sample aliquot using added 235U and 23 l~a tracers from the ~spectra of the separated fractions. The technique was validated by quality control analyses.
Journal of inorganic biochemistry, 2009
The quantitative description of the interactions of uranium with blood serum components is of hig... more The quantitative description of the interactions of uranium with blood serum components is of high relevance for a rational design of molecules suitable for in vivo chelation of uranium. We have determined the stability constants for the complexation of U(VI) with human serum transferrin and albumin by time-resolved laser-induced fluorescence spectroscopy and difference ultraviolet spectroscopy. Both proteins interact strongly with U(VI), forming ternary complexes with carbonate acting as a synergistic anion. Together with literature data describing the interaction of U(VI) with low molecular weight inorganic and organic serum components, the speciation of U(VI) in blood serum was calculated. In agreement with published experimental data, the model calculation shows that complexation with proteins and carbonate ion governs U(VI) speciation; 35% of U(VI) is bound to proteins and 65% to carbonate. Among the protein pool, albumin is the main protein interacting with U(VI). In addition,...
Czechoslovak Journal of Physics, 2006
The paper addresses identification of industries and activities handling NORM and inventory of TE... more The paper addresses identification of industries and activities handling NORM and inventory of TENORM in Slovenia. The identification is based on survey of historical information available, results published in scientific papers, research reports made by research institutions within Slovenia, as well as original research aimed at obtaining more detailed picture of the areas investigated. For this purpose, gamma dose-rate measurements were performed on site, sampled TENORM/NORM materials were measured by high-resolution gamma spectrometry for determination of 210 Pb, 238 U, 232 Th, 228 Th and 226 Ra. Waste water and ground water samples were analysed for 238 U, 226 Ra and 210 Pb using RNAA, LSC and beta proportional counting. The inventory of the investigated sites is presented, giving the information on amounts of the deposited wastes, specific activities of the natural radionuclides and geographical distribution of the inventories in Slovenia.
Czechoslovak Journal of Physics, 2006
A new RNAA procedure was developed for simultaneous determination of low levels of I and Mn in bi... more A new RNAA procedure was developed for simultaneous determination of low levels of I and Mn in biological materials. The procedure is based on sample decomposition by alkaline-oxidative fusion in a mixture of Na 2 O 2 + NaOH at 900°C followed by extraction of elementary iodine by chloroform. Subsequently, Mn is separated either by precipitation of hydrated MnO 2 or by extraction of the Mn-diethyldithiocarbamate complex in chloroform. The accuracy of the RNAA procedure developed was proven by analysis of several low-level biological reference materials. Detection limits of I and Mn achievable in both institutes and the degree of interference for the Mn determination due to 56 Fe(n,p) 56 Mn reaction with fast neutrons are discussed. 128 I (T 1/2 = 24.99 min, main E γ = 442.9 keV (16.9%)) and 56 Mn (T 1/2 = 2.58 h, main E γ = 846.8 keV (98.9%)). Radiochemical procedures for separation of individual elements are frequently used in the determination of elements forming short-lived radionuclides to be able to cope with the short half-lives and different chemical properties of the radionuclides concerned. However, for analysis of precious samples, e.g., human tissues, it is advantageous to use RNAA procedures for determination of more elements in one sample aliquot whenever feasible. For this purpose, a new RNAA procedure was developed for simultaneous determination of low levels of I and Mn in biological materials.
![Research paper thumbnail of Investigation of para-sulfonatocalix[n]arenes [n = 6, 8] as potential chelates for 230U](https://attachments.academia-assets.com/87508875/thumbnails/1.jpg)
](Dalton Transactions, 2010
Literature reports of the efficacy of para-sulfonatocalix[6]and calix[8]-arenes as U(VI) complexa... more Literature reports of the efficacy of para-sulfonatocalix[6]and calix[8]-arenes as U(VI) complexants indicated that they might be useful for in vivo chelation of the novel therapeutic alhpa-emitter 230 U. We have studied the complexation of U(VI) with parasulfonatocalix[6]arene and para-sulfonatocalix[8]arene by time resolved laser induced fluorescence spectroscopy and using competition methods with Chelex resin and 4-(2pyridylazo)resorcinol in simplified and in biological media. New thermodynamic parameters describing the stability of U(VI)-para-sulfonatocalix[n]arene [n = 6, 8] complexes were obtained. Although the interactions are strong, the complexes do not exhibit sufficient stability to compete with carbonate ions and serum proteins for complexation of U(VI) under physiological conditions.
Accreditation and Quality Assurance, 2001
A proficiency test (PT) was carried out to investigate the quality of laboratory results measurin... more A proficiency test (PT) was carried out to investigate the quality of laboratory results measuring trace elements in sewage sludge. The scheme relied on reference values, established through flame atomic absorption spectroscopy and instrumental neutron activation analysis. Within the framework of the project, ”Proficiency testing in Central and Eastern European Countries”, the measurements were done in parallel using induced coupled plasma mass spectrometry. This paper discusses the design of the PTS, the metrological concepts behind it and the way in which it was operated. The discussion includes the estimation of measurement uncertainty of the reference values obtained, homogeneity testing and its uncertainty evaluation, as well as all relevant quality assurance aspects. From the results, it can be concluded that all measurement methods involved agree within their respective uncertainties. Furthermore, it can be concluded that it is feasible to operate a proficiency test of trace elements in sewage sludge using reference values. The agreement between the reference values and the consensus values is satisfactory.
Microchimica Acta, 2008
A procedure is described for the determination of cobalt in biological materials, based on postir... more A procedure is described for the determination of cobalt in biological materials, based on postirradiation separation radiochemical neutron activation analysis (RNAA) using the short-lived induced radionuclide 60m Co. 60m Co has been rarely used as an indicator radionuclide in NAA due to low concentrations usually found in biological materials and due to its short-half life (t 1=2 ¼ 10.5 min). Using a procedure based on dissolution of the irradiated sample, precipitation of Co with sodium diethyldithiocarbamate, extraction of the complexes formed into toluene, purification and counting by gamma spectrometry, Co was determined in biological materials at ng g À1 levels. For evaluation of gamma spectra, the Hypermet-PC and HyperLab 2002 Gamma Spectroscopy systems were used. Differences between these software programs are discussed. The results of the analyzed biological materials (reference materials), together with the identified uncertainty sources, are presented. The RNAA method allows rapid, robust and simple separation of short-lived 60m Co from neutron irradiated biological samples in high and reproducible yield (83%), with adequate sensitivity for routine use, reducing the time necessary for the irradiation, processing and measurement in comparison to classical NAA using 60 Co, thus retaining the important advantage of NAA as a blank free technique.
Journal of Radioanalytical and Nuclear Chemistry, 2016
In the frame of the accountancy measurements of the fissile materials, reliable determinations of... more In the frame of the accountancy measurements of the fissile materials, reliable determinations of the plutonium and uranium content in spent nuclear fuel are required to comply with international safeguards agreements. Large-sized dried (LSD) spikes of enriched 235 U and 239 Pu for isotope dilution mass spectrometry (IDMS) analysis are routinely applied in reprocessing plants for this purpose. A correct characterisation of these elements is a pre-requirement for achieving high accuracy in IDMS analyses. This paper will present the results of external verification measurements of such LSD spikes performed by the European Commission and the International Atomic Energy Agency.
International Journal of Mass Spectrometry, 2014
Environmental Radiochemical Analysis II
Journal de Physique IV (Proceedings), 2003
The routine determination of the activity concentrations of uranium isotopes (mU, mU and 234U), t... more The routine determination of the activity concentrations of uranium isotopes (mU, mU and 234U), thorium isotopes (212Th, 230TI, and 228Th), 23'Pa, 22'Ra, 210Pb and 210pro in the environment is one of the most important tasks in uranium mining areas. Natural radionuclides contribute negligibly to the extemal radiation dose, but in the case of ingestion or inhalation can represent a very serious hazard. The objective of this study was to determine the activities of uranium and its decay products 230Th, 231Pa, 226Ra, 210Pb alld 210po in sediments and water below sources of contamination (uranium mine, disposal sites and individual inflows) using gamma and alpha spectrometry, beta counting, me liquid scintillation technique and radiochemical neutron activation analysis.
Applied Radiation and Isotopes, 2010
Radium-226 is one of the best known long-lived a-emitters abundantly present in the environment. ... more Radium-226 is one of the best known long-lived a-emitters abundantly present in the environment. The determination of radium isotopes in environmental samples usually requires a demanding chemical separation before measurement and quantification. Each step in the chemical separation process can involve losses of the analyte, therefore it is of vital importance that the recovery of the whole radiochemical procedure is evaluated. The emphasis of the work presented was determination of the chemical recovery using the different yield tracers Ra-223, Ra-225 and Ba-133.
Accreditation and Quality Assurance, 2011
Calcium is an important constituent of mineral like calcite, dolomite, gypsum and bio-ceramic raw... more Calcium is an important constituent of mineral like calcite, dolomite, gypsum and bio-ceramic raw material like hydroxyapatite. Those are frequently used for the manufacture of cement, mortar, glass, synthetic ceramic bone supplement, dental enamel, etc. Determination of exact quantity of calcium in those materials is therefore very essential. The calcium content has been determined complexometrically in a ceramic raw material at pH 12, using di-sodium salt of EDTA. The major sources of uncertainty of the results of measurement are contributions from repeatability, standardization of EDTA, volume measurement by volumetric flask, burette, pipette and end point detection. Sources of uncertainty have been identified and combined by following the EURACHEM guidelines. The results show that the major sources of uncertainty arise from standardization, repeatability of the experiment and end point detection by burette. Cause-effect diagram has been drawn to explain the uncertainty budget.
Uranium in the Aquatic Environment, 2002
The uranium mine and mill at Žirovski vrh (RŽV), Slovenia stopped mining and milling in 1990. Mil... more The uranium mine and mill at Žirovski vrh (RŽV), Slovenia stopped mining and milling in 1990. Mill tailings containing about 20 % moisture were transported to a disposal site called Boršt. The objective of this work was to study the migration of the radionuclides U-238, Ra-226, Pb-210 and Po-210 from the Boršt waste disposal site. For determination of radionuclides, gamma and alpha spectrometry, beta counting, neutron activation analysis and liquid scintillation techniques were used.
Radiochemical neutron activation analysis (RNAA) is an excellent method for determining uranium a... more Radiochemical neutron activation analysis (RNAA) is an excellent method for determining uranium and thorium; it offers unique possibilities for their ultratrace analysis using selective radiochemical separations. Regarding the favourably sensitive nuclear characteristics of uranium and of thorium with respect to RNAA, but the different half-lives of their induced nuclides, two different approaches were used. In the first approach uranium and thorium were determined separately via U, Np and Pa. In the second approach these elements were determined simultaneously in a single sample using U and/or Np and Pa. Isolation of induced nuclides was based on separation by extraction and/or anion exchange chromatography. Chemical yields were measured in each sample aliquot using added U, Np and Pa radioisotopic tracers.
Examples on traceability, measurement uncertainty and validation for measurements of retinol and ... more Examples on traceability, measurement uncertainty and validation for measurements of retinol and α‐tocopherol in human serum, cyclamate in soft drinks, arsenic in groundwater, sodium chloride in milk products and total organic carbon in waste water are presented in this book. Additionally, the idea and structure of the TrainMiC® examples, which complement the TrainMiC® theoretical presentations, are described in detail to give a complete overview of the TrainMiC® teaching material. HOW TO OBTAIN EU PUBLICATIONS Free publications: • via EU Bookshop (http://bookshop.europa.eu); • at the European Union’s representations or delegations. You can obtain their contact details on the Internet (http://ec.europa.eu) or by sending a fax to +352 2929-42758. Priced publications: • via EU Bookshop (http://bookshop.europa.eu). Priced subscriptions (e.g. annual series of the Official Journal of the European Union and reports of cases before the Court of Justice of the European Union): • via one of ...
... The background values, because of the lack of shielding, were quite high (~35 cpm, 226Ra win... more ... The background values, because of the lack of shielding, were quite high (~35 cpm, 226Ra window). * E-mail: urska.repinc@ijs.si 02365731/2002/USD 17.00 ... Meth., 165 (1975) 345. 1. I. KOBAL, M. SHAHIN, J. KRISTAN, M. SENEGAC ∨ NIK, Health Phys., 27 (1974) 381. ...
Journal of Radioanalytical and Nuclear Chemistry Articles, 1995
A method for the simultaneous, radiochemical neutron activation analysis of uranium and thorium a... more A method for the simultaneous, radiochemical neutron activation analysis of uranium and thorium at trace levels in biological materials is described, based on a technique known as LICSIR, in which a 23 double neutron irradiation is employed. In the first, long irradiation '"Pa (27.0 d) is induced by neutron capture on 232Th and then the sample is cooled for several weeks. A second short irradiation to induce 23~' 23 U (23.5 m) is followed by a rapid sequential radiochemical separation by solvent extraction of 9U with TBP and 233pa with TOPO. Chemical yields of 239U and 233pa were measured for each sample aliquot using added 235U and 23 l~a tracers from the ~spectra of the separated fractions. The technique was validated by quality control analyses.
Journal of inorganic biochemistry, 2009
The quantitative description of the interactions of uranium with blood serum components is of hig... more The quantitative description of the interactions of uranium with blood serum components is of high relevance for a rational design of molecules suitable for in vivo chelation of uranium. We have determined the stability constants for the complexation of U(VI) with human serum transferrin and albumin by time-resolved laser-induced fluorescence spectroscopy and difference ultraviolet spectroscopy. Both proteins interact strongly with U(VI), forming ternary complexes with carbonate acting as a synergistic anion. Together with literature data describing the interaction of U(VI) with low molecular weight inorganic and organic serum components, the speciation of U(VI) in blood serum was calculated. In agreement with published experimental data, the model calculation shows that complexation with proteins and carbonate ion governs U(VI) speciation; 35% of U(VI) is bound to proteins and 65% to carbonate. Among the protein pool, albumin is the main protein interacting with U(VI). In addition,...
Czechoslovak Journal of Physics, 2006
The paper addresses identification of industries and activities handling NORM and inventory of TE... more The paper addresses identification of industries and activities handling NORM and inventory of TENORM in Slovenia. The identification is based on survey of historical information available, results published in scientific papers, research reports made by research institutions within Slovenia, as well as original research aimed at obtaining more detailed picture of the areas investigated. For this purpose, gamma dose-rate measurements were performed on site, sampled TENORM/NORM materials were measured by high-resolution gamma spectrometry for determination of 210 Pb, 238 U, 232 Th, 228 Th and 226 Ra. Waste water and ground water samples were analysed for 238 U, 226 Ra and 210 Pb using RNAA, LSC and beta proportional counting. The inventory of the investigated sites is presented, giving the information on amounts of the deposited wastes, specific activities of the natural radionuclides and geographical distribution of the inventories in Slovenia.
Czechoslovak Journal of Physics, 2006
A new RNAA procedure was developed for simultaneous determination of low levels of I and Mn in bi... more A new RNAA procedure was developed for simultaneous determination of low levels of I and Mn in biological materials. The procedure is based on sample decomposition by alkaline-oxidative fusion in a mixture of Na 2 O 2 + NaOH at 900°C followed by extraction of elementary iodine by chloroform. Subsequently, Mn is separated either by precipitation of hydrated MnO 2 or by extraction of the Mn-diethyldithiocarbamate complex in chloroform. The accuracy of the RNAA procedure developed was proven by analysis of several low-level biological reference materials. Detection limits of I and Mn achievable in both institutes and the degree of interference for the Mn determination due to 56 Fe(n,p) 56 Mn reaction with fast neutrons are discussed. 128 I (T 1/2 = 24.99 min, main E γ = 442.9 keV (16.9%)) and 56 Mn (T 1/2 = 2.58 h, main E γ = 846.8 keV (98.9%)). Radiochemical procedures for separation of individual elements are frequently used in the determination of elements forming short-lived radionuclides to be able to cope with the short half-lives and different chemical properties of the radionuclides concerned. However, for analysis of precious samples, e.g., human tissues, it is advantageous to use RNAA procedures for determination of more elements in one sample aliquot whenever feasible. For this purpose, a new RNAA procedure was developed for simultaneous determination of low levels of I and Mn in biological materials.
Dalton Transactions, 2010
Literature reports of the efficacy of para-sulfonatocalix[6]and calix[8]-arenes as U(VI) complexa... more Literature reports of the efficacy of para-sulfonatocalix[6]and calix[8]-arenes as U(VI) complexants indicated that they might be useful for in vivo chelation of the novel therapeutic alhpa-emitter 230 U. We have studied the complexation of U(VI) with parasulfonatocalix[6]arene and para-sulfonatocalix[8]arene by time resolved laser induced fluorescence spectroscopy and using competition methods with Chelex resin and 4-(2pyridylazo)resorcinol in simplified and in biological media. New thermodynamic parameters describing the stability of U(VI)-para-sulfonatocalix[n]arene [n = 6, 8] complexes were obtained. Although the interactions are strong, the complexes do not exhibit sufficient stability to compete with carbonate ions and serum proteins for complexation of U(VI) under physiological conditions.
Accreditation and Quality Assurance, 2001
A proficiency test (PT) was carried out to investigate the quality of laboratory results measurin... more A proficiency test (PT) was carried out to investigate the quality of laboratory results measuring trace elements in sewage sludge. The scheme relied on reference values, established through flame atomic absorption spectroscopy and instrumental neutron activation analysis. Within the framework of the project, ”Proficiency testing in Central and Eastern European Countries”, the measurements were done in parallel using induced coupled plasma mass spectrometry. This paper discusses the design of the PTS, the metrological concepts behind it and the way in which it was operated. The discussion includes the estimation of measurement uncertainty of the reference values obtained, homogeneity testing and its uncertainty evaluation, as well as all relevant quality assurance aspects. From the results, it can be concluded that all measurement methods involved agree within their respective uncertainties. Furthermore, it can be concluded that it is feasible to operate a proficiency test of trace elements in sewage sludge using reference values. The agreement between the reference values and the consensus values is satisfactory.
Microchimica Acta, 2008
A procedure is described for the determination of cobalt in biological materials, based on postir... more A procedure is described for the determination of cobalt in biological materials, based on postirradiation separation radiochemical neutron activation analysis (RNAA) using the short-lived induced radionuclide 60m Co. 60m Co has been rarely used as an indicator radionuclide in NAA due to low concentrations usually found in biological materials and due to its short-half life (t 1=2 ¼ 10.5 min). Using a procedure based on dissolution of the irradiated sample, precipitation of Co with sodium diethyldithiocarbamate, extraction of the complexes formed into toluene, purification and counting by gamma spectrometry, Co was determined in biological materials at ng g À1 levels. For evaluation of gamma spectra, the Hypermet-PC and HyperLab 2002 Gamma Spectroscopy systems were used. Differences between these software programs are discussed. The results of the analyzed biological materials (reference materials), together with the identified uncertainty sources, are presented. The RNAA method allows rapid, robust and simple separation of short-lived 60m Co from neutron irradiated biological samples in high and reproducible yield (83%), with adequate sensitivity for routine use, reducing the time necessary for the irradiation, processing and measurement in comparison to classical NAA using 60 Co, thus retaining the important advantage of NAA as a blank free technique.