Determination of copper in biological samples by substoichiometric neutron activation analysis

A method has been described for the determination of trace amounts of copper in biological samples by thermal neutron activation analysis, involving radiochemical separation of copper from irradiated matrix employing substoichiometric extraction of Cu/II/ with 2-mercaptobenzothiazole /2-HMBT/ into chloroform. 4.01 g of Cu/II/ can be determined with an accuracy of 3.13% and precision of 1.08%.     

Simultaneous determination of antimony,arsenic and copper by neutron activation analysis

A rapid procedure has been developed for the mutual separation of antimony and arsenic using tribenzylamine as the extracting agent. The extraction behaviours of Sb(III), Sb(V), As(III), As(V) and Au(III) have been studied as a function of the acidity of the aqueous phase. Various factors which affect the extraction of these complexes have been studied and optimized. The procedure was then applied to lead base alloy for the simultaneous determination of antimony, arsenic and copper. Chemical recoveries were quantitative and only about one hour is required for the chemical processing of duplicate samples.     

Determination of Hg in biological samples by substoichiometric neutron activation analysis

The method described here involves the irradiation of biological samples and a g quantity of standard with thermal neutrons at the self-serve position in the CIRUS reactor, followed by dissolution of the sample and standard in the presence of milligram amounts of carrier. Both the sample and the standard are subjected to substoichiometric extraction under controlled experimental conditions with ethyl thioacetoacetate into chloroform. An aliquot of the organic phase is counted on a -spectrometer. The concentration of Hg in various biological samples and the accuracy, precision, and sensitivity of the method are discussed.     

Simultaneous determination of arsenic and antimony in environmental samples by radiochemical neutron activation analysis

A radiochemical separation procedure using an inorganic exchanger, tin dioxide (TDO), for the separation of arsenic from antimony is reported here. This separation avoids the interference of 564 keV gamma-ray of¹²²Sb in the measurement of the 559 keV gamma-ray of⁷⁶As in neutron activation analysis. Environmental samples, after neutron irradiation and digestion, are taken up in 1M HCl–0.1M HF and passed through a TDO column which selectively retains arsenic. The effluent from the TDO column, after proper conditioning, is passed through an anion exchange column for quantitative retention of antimony. The procedure has been utilized for arsenic and antimony determination in NBS Orchard Leaves and NBS Albacore Tuna.     

Simultaneous estimation of copper, zinc, cadmium and mercury in biological material by neutron activation analysis

Simultaneous determination of copper, zinc, cadmium and mercury with high sensitivity is possible by neutron activation analysis. After irradiation, the samples are digested and an initial separation of the four elements made by means of an ion-exchange resin. The elements in the separated fractions are then treated to give radio-chemical purity, precipitated, and their activities measured. A purely instrumental technique for the analysis of zinc in samples of biological material is also described. The samples are irradiated for a week and after the activity has decayed for about three months it is measured on a gamma-spectrometer.     

Simultaneous determination of mercury and selenium in biological materials by radiochemical neutron activation analysis

A simple and sensitive radiochemical neutron activation analysis (RNAA) method has been developed for the simultaneous determination of mercury and selenium in biological materials. The radiochemical procedure is based upon the digestion of irradiated samples with sulphuric and nitric acids followed by subsequent extractions of mercury and selenium into toluene, first of mercury from 7.5 M H₂SO₄-0.01M HBr media and after of selenium from 7M H₂SO₄-1 M HBr media. After washing of the organic phases with similar media, the mercury bromide was back-extracted into 0.034M EDTA in 5% aqueous ammonia and the selenium bromide into 0.14M H₂O₂ in aqueous solution. The¹⁹⁷Hg and the⁷⁵Se were counted on a Ge(Li) detector. The precision and accuracy of the method was checked by analysing NBS Standard Reference Materials: orchard leaves and bovine liver.     

Redox substoichiometric determination of arsenic in biological materials by neutron activation analysis

A redox substoichiometry is proposed for an accurate and precise determination of arsenic. This method is based on the substoichiometric oxidation of trivalent arsenic to pentavalent with potassium bromate or ceric sulfate followed by the separation of these species by thionalide extraction of trivalent arsenic. It was applied to neutron activation analysis of arsenic in the NBS SRM Orchard Leaves and the Shark Powder. The results were obtained with an excellent accuracy and precision.     

Simultaneous determination of arsenic,mercury, antimony and selenium in biological materials with prior collection of gaseous products followed by neutron activation analysis

A method combining prior collection of gaseous products with subsequent neutron activation analysis has been developed for simultaneous determination of traces of arsenic, mercury, antimony and selenium in biological materials. The generation of hydrides of arsenic, antimony and selenium and cold vapor of mercury in the vapor generaion and collection system was investigated by the use of radiotracers of the respective elements. The result indicates that selenium and mercury can be completely evaporated from the digested sample solution in 5M HCl with the addition of 5% sodium tetrahydroborate solution, while additional reduction proces by potassium iodide and ascorbic acid is needed for complete evaporation of arsenic and antimony. The gaseous products were collected in a quartz tube for neutron irradiation. The detection limits of these elements were fount to be in the range of 10^–7 to 10^–8 g under the present experimental conditions. The reliability was checked with NBS standard reference materials.     

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

Summary Regarding 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.     

Rapid determination of antimony in biological and environmental samples using instrumental neutron activation analysis

A rapid non-destructive activation analysis method has been developed for the determination of antimony. A high resolution low energy Ge detector is used to measure the 61.6 keV γ-ray from^122mSb (T=4.2 min). Sensitivities and detection limits for biological and environmental samples activated with thermal and epithermal neutrons are listed. The time required for the anlaysis is about 12 min per sample using thermal activation and 22 minutes using epithermal activation analysis.     

Simultaneous radiochemical neutron activation analysis of iodine, uranium and mercury in biological and environmental samples

The determination of medium and long-lived nuclides can be combined with short-lived ones if a medium or long irradiation is made prior to the short irradiation and radiochemical processing. Thus, an RNAA method previously developed for determination of iodine based on the reaction¹²⁷I(n,)¹²⁸I (T _1/2=25 m) using oxygen flask ignition of the irradiated sample, followed by solvent extraction with an iodine-iodide redox cycle, was combined with an overnight preirradiation to induce the²³⁵U fission product¹³³I (T _1/2=20.8 h). By reactivating the sample, cooled 1–2 days after the first irradiation, for few minutes both¹²⁸I and¹³³I could be quantified in the separated iodine fraction. Non-combustible inorganic materials (e.g., sediment, soil, etc.) can be successfully ignited after mixing with excess cellulose powder. Chemical yields for iodine were determined spectrophotometrically in the organic phase, while homogeneously spiked Whatman cellulose powder was used as uranium standard. Mercury is also released on ignition and collected in the absorbing solution, from where it was separated by toluene extraction. Its chemical yield was determined for each aliquot using²⁰³Hg tracer and counting on an LEPD. Results for some suitable SRMs are presented, and the general features of the double irradiation technique discussed.     

Simultaneous determination of trace uranium and vanadium in biological samples by radiochemical neutron activation analysis

Summary A radiochemical neutron activation analysis (RNAA) for simultaneous determination of uranium and vanadium in a single sample at trace levels is described. The method is based on post-irradiation wet-ashing and solvent extraction of vanadium with N-benzoyl-N-phenyl-hydroxylamine reagent. From the remaining aqueous phase, uranium is extracted into a toluene solution of tri-n-butyl phosphate. The chemical yields are determined spectrophotometrically for vanadium and by gamma-counting of the added natural uranium carrier for uranium. The method was evaluated by the analysis of reference materials and the results showed a good agreement with the certified values. The method was applied to the determination of vanadium and uranium in five military total diet samples in Slovenia.     

Simultaneous determination of mercury and gold in bismuth by neutron activation analysis

After adding mercury as carrier, trace amounts of mercury and gold were simultaneously separated from bismuth by coprecipitating with sulfur produced by the decomposition of bismuth sulfide. The sulfur was filtered on a membrane filter, and the γ-activities were measured with a Ge(Li) detector. The recoveries were quantitative and the measurement of chemical yield was unnecessary. 123 ppm of mercury and 8 ppb of gold in a bismuth sample were determined simultaneously.     

Determination of arsenic and antimony in biological materials by solvent extraction and neutron activation

Arsenic and antimony in digested biological samples can be extracted with pyrrolidinecarbodithioate at pH 1 into chloroform and stripped with nitric acid for neutron-activation analysis (NAA). The extraction method eliminates interferences from matrix species, including Br and Na, making the accurate determination of low levels of As and Sb in biological materials feasible. The detection limits under the experimental conditions used are 0.005 and 0.006 mug/g for arsenic and antimony, respectively. A comparison of the results obtained for As and Sb in NBS biological standards by this method and by non-destructive instrumental neutron-activation analysis (INAA) is also given.     

Simultaneous neutron-activation determination of selenium and mercury in biological samples by volatilization

A method is described for the determination of selenium together with mercury in biological samples by neutron-activation analysis based on quantitative volatilization of both elements. The technique originally developed for mercury, based on pyrolysis with filtration of undesirable impurities and selective trapping from the gas phase, is now extended to selenium. The radionuclides (197)Hg and (75)Se, from one sample, are trapped separately and counted in a well-type NaI(Tl) detector and gamma-spectrometer for maximum sensitivity. The method has been tested by comparative analyses and analyses of standard biological materials, and gives good results. It is simple and is especially effective in studies of the interaction of mercury and selenium in biological systems; a positive correlation for these elements was found for human tissues. On décrit une méthode pour le dosage du sélénium conjointement au mercure dans les échantillons biologiques par analyse par activation de neutrons basée sur la volatilisation quantitative des deux éléments. La techniqu initialement développée pour le mercure, basée sur la pyrolyse avec filtration des impuretés indésirables et captage sélectif de la phase gazeuse, est maintenant étendue au sélénium. Les radionuclides (197)Hg et (75)Se, d'un échantillon, sont captés séparément dans un détecteur NaI(Tl) du type puits et un spectromètre gamma pour la sensibilité maximale. La méthode a été essayée par des analyses comparatives et des analyses de produits biologiques étalons, et donne de bons résultats. Elle est simple et particulièrement efficace dans les études de l'interaction du mercure et du sélénium dans des systèmes biologiques; on a trouvé une corrélation positive pour ces éléments pour des tissus humains.     

Determination of Sc in rock samples by substoichiometric thermal neutron activation analysis

A rapid, selective and simple method has been developed for the determination of Sc in rock samples by thermal neutron activation analysis, employing substoichiometric solvent extraction of Sc(III) with alizarin into 1-octanol. Two samples and a standard can be processed and counted within three hours.     

Determination of trace level mercury in biological and environmental samples by neutron activation analysis

Sorptivity studies with Chelex 100 column indicated chloride to be the best medium for the sorption of mercury. A radiochemical separation procedure has been developed for the determination of mercury by neutron activation analysis utilizing sorption of mercury on Chelex 100. The method was checked with Orchard Leaves and Tuna Fish standards from the National Institute of Standards and Technology.     

Simultaneous voltammetric determination of molybdenum and copper in biological samples

 A selective, sensitive and reliable voltammetric method for the simultaneous determination of Cu and Mo is developed. Both metals form complexes with 8-hydroxyquinoline (oxine). Mo gives two reduction peaks with oxine in acidic chloride media at −0.52 V and −0.58 V, while copper exhibits only one at −0.14 V. Common heavy metals do not interfere at all. The limit of detection is 0.29 ng/ml for Mo and 0.14 ng/ml for Cu after preconcentration on the hanging mercury drop electrode for 30 s at −0.2 V. The R.S.D. at a concentration level of 10 ng/ml is 3.8% for Cu and 5.3% for Mo. The method is applied to different biological samples. Received: 15 January 1996/Revised: 11 April 1996/Accepted: 16 April 1996     

Simultaneous determination of antimony and chlorine in synthetic rubbers by 14 MeV neutron activation analysis

A nondestructive method for the analysis of Sb and Cl in synthetic rubbers by 14 MeV neutron activation analysis has been developed and evaluated by comparisons with microanalytical and thermal neutron activation analysis results. The method is most precise when a rubber with known amounts of Sb and Cl is used as a standard. Samples containing 0.07 to 2.5 wt.% Sb and 2.5 to 15.9 wt.% Cl have been analyzed and precision for the method is 10% or better. Antimony and Cl detection limits are 0.02 and 0.5 wt.% respectively. Agreement among the three methods is excellent; the thermal activation analysis method is more precise and simpler to apply if only Sb needs to be determined in a sample. This work was supported by the U.S. Department of Energy (DOE) under Contract DE-AC04-76-DP00789. A U.S. DOE facility.     

An accurate method for the determination of copper in biological materials by neutron activation analysis and extraction chromatography

Distribution coefficients of 14 elements between LIX 70 in toluene and aqueous 1M NaNO₃ solution containing varying concentrations of HCl or suitable buffer, respectively, were determined by batch equilibration. It was shown that very selective separation of Cu from other elements can be achieved on columns with LIX 70 supported on Bio-Beads SM-1. Highly accurate and precise method for the determination of trace amounts of Cu in biological materials was devised by combining NAA with extraction chromatography. Results of copper determination in NBS 1570 /Spinach/, IAEA H-4 /Animal muscle/ and IAEA V-8 /Rye flour/ are presented.