Neutron activation analysis of biological materials for sub ppm amount of mercury without determining the chemical yield

A simple method for the determination of sub ppm amounts of mercury in various biological materials by neutron activation analysis is described. Irradiated samples were decomposed with H₂SO₄-fuming HNO₃ mixture and mercury selectively isolated by ion exchange chromatography using Dowex 50WX2 [H⁺] and Dowex 1X4 [Br⁻] columns in HBr medium. Finally the activity of¹⁹⁷Hg fixed on an anion exchange resin was measured either with a Ge(Li) or a NaI (Tl) detector. Both the high radiochemical purity of mercury and the practically quantitative recovery were achieved thus eliminating the necessity of determining the chemical yield. The method was used for the determination of mercury in flour, milk, butter, margarine, fish, etc.     

Neutron activation analysis of gold and iridium in steel

A method of determination of trace gold and iridium in steel is presented. The samples were preconcentrated with an anion exchanger. The chemical recoveries were determined by an isotope tracer technique using¹⁹⁸Au and¹⁹²Ir.     

Neutron activation analysis for determination of cerium trace impurity in high purity lanthanum oxide

Cerium trace impurity in high purity lanthanum oxide (99.99%) has been determined by NAA after pre-separation of La matrix. In this method, the sample was dissolved in conc. nitric acid and diluted with water. The final concentration of solution is about 0.1M of nitric acid. It was passed through a MnO₂ column. Under these conditions cerium is retained on the column quantitatively without retaining lathanum. Cerium is eluted with 4M nitric acid. The recoveries of Ce were checked with tracers and by standard addition to lanthanum oxide matrices. Results obtained on a high purity lanthanum oxide are reported here.     

Neutron activation analysis for assessing chemical composition of dry dog foods

Brazil holds the second largest population of domestic dogs in the world, with 33 million dogs, only behind the United States. The annual consumption of dog food in the country is 1.75 million tons, corresponding to the World’s sixth in trade turnover. Dog food is supposed to be a complete and balanced diet, formulated with high quality ingredients. All nutrients and minerals required for an adequate nutrition of dogs are added to the formulation to ensure longevity and welfare. In this context, the present study aimed at assessing the chemical composition of dry dog foods commercialized in Brazil. Thirty-four samples were acquired in the local market of Piracicaba and analyzed by instrumental neutron activation analysis (INAA) to determine the elements As, Br, Ca, Co, Cr, Cs, Fe, K, La, Na, Rb, Sb, Sc, Se, U, and Zn. In general, the concentrations of Ca, Fe, K, Na, and Zn complied with the values required by the Association of American Feed Control Officials (AAFCO). To evaluate the safety of dog food commercialized in Brazil, further investigation is necessary to better understand the presence of toxic elements found in this study, i.e. Sb and U. INAA was useful for the screening analysis of different types and brands of dry dog foods for the determination of both essential and toxic elements.     

Neutron activation analysis of manganese and nickel in commercial steel samples

The non-destructive thermal neutron activation analysis of some commercially available steel samples viz. SS-316, SS-310, SS-304, Tiscral, CA55 and EN 8 is carried out using a²⁵²Cf source. The manganese content of these steel samples is estimated by measuring the -activity of⁵⁶Mn using a single channel analyzer on integration mode and a NaI/Tl/ detector as well as using a high purity germanium detector coupled to a 4K multichannel analyzer. The results obtained by both procedures show reasonable agreement with each other. The nickel content of the various steel samples is also estimated.     

Neutron activation analysis of corrosion products from gold coated ear piercing studs

Neutron activation analysis was applied to the determination of elements Au, Cr, Fe, Ni and Zn released in NaCl solution and in a culture medium in which gold coated studs were immersed for corrosion tests. The coating defects and corrosion effects on the stud surfaces were studied by scanning electron microscopy and energy dispersive spectroscopy analysis. The cytotoxicity assay of culture medium from corrosion test showed toxicity in a culture of mammalian cells.     

Neutron activation determination of gold in rocks using dibutyl sulfide extraction for gold separation

A rapid method for the determination of gold in rocks by neutron activation was developed. The method is based on the quantitative and specific separation of gold with dialkyl sulfide extraction.     

Neutron activation analysis of the NIST Bovine Serum Standard Reference Material using chemical separations

Summary The US National Institute of Standards and Technology is currently in the process of certifying a Bovine Serum Standard Reference Material. In addition to elements normally considered to be of clinical interest, a number of other elements, which are analytically more difficult to determine yet are of importance from either a nutritional or toxicological viewpoint, are being determined by a variety of analytical techniques. Neutron activation analysis in combination with appropriate pre- or post-irradiation chemical separations, has been used to determine many of these difficult elements.

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Neutronenaktivierungsanalyse des Standardreferenzmaterials NIST Bovine Serum mit Hilfe chemischer Trennungen

     

Neutron activation analysis of manganese in Japanese iron reference standard materials, with large amounts of manganese

Effects of pile-up and neutron self-shielding were experimentally corrected in INAA of manganese and vanadium in iron and ferro- and silicon manganese samples supplied by the Japan Iron and Steel Federation. A pile-up correction curve was drawn as a function of total gamma count rate for each Ge detector by a ⁶⁰Co source set at a fixed position and ²⁴Na and ¹³⁷Cs sources moved to vary the gamma-ray intensities. The neutron self-shielding effect was examined by varying the weight of irradiated samples. The effect was negligible for iron samples containing a few percent manganese when samples of less than 0.2 g were irradiated. Good results were obtained for silicon and ferro-manganese by repeated analyses of samples less than 0.02 g in order to avoid the influence of the neutron self-shielding and sample inhomogeneity. A good result can be also obtained from the maximum point of a quadratic equation derived from the relationship between apparent manganese concentrations and sample weight in the range clearly affected by self-shielding. The water dilution after acid dissolution was also effective for samples of high manganese content if special caution was given to regulate the concentration of chloride having a large neutron absorption cross section.     

Neutron activation analysis for the routine clinical investigation of osteoporosis

Neutron activation analysis provides a useful clinical test to assess bone mass status in vivo. The neutron flux is obtained from Pu/Be sources and⁴⁹Ca activity is measured by NaI detectors. For diagnostic value, the⁴⁹Ca measurement is related to the mean value for normal subjects of the same body size. This normalized index, our CaBI, is used extensively to diagnose the bone loss associated with osteoporosis and to asses changes in bone mass with progression of disease and in response to treatments. Our facility operates at maximum capacity (35 tests/wk.). The hospital location and the dependability and ease of operation (provided by neutron sources) have facilitated extensive clinical use.     

Neutron activation analysis for osmium and ruthenium in platinum

A sensitive procedure for the simultaneous determination of trace levels of osmium and ruthenium in platinum, by thermal neutron activation analysis utilizing γ-ray spectrometry, was developed. The radiochemical separation method utilized perchloric acid for a selective oxidation of osmium and ruthenium to the volatile tetroxides. The distillation of the tetroxides greatly reduced the radiation hazard presented by the bulk of the activities in the matrix. Activities of 15-day¹⁹¹Os and 40-day¹⁰⁴Ru were measured by accumulation of pulses from a 3″ diameter NaI(Tl) crystal detector. Analyses of γ-ray spectra were achieved using digital computer techniques. The procedure provided analyses for a high purity platinum stock of 0.032±0.007 ppm Os and 0.044±0.005 ppm Ru. Work was performed at the Ames Laboratory of the U. S. Atomic Energy Commission, Contribution No. 3073.     

Neutron activation analysis of water and waste

The neutron activation method has been applied to the determination of Ag, Cd, Co, Cr, Cu, Fe, Hg, Mo, Se and Zn in waters and wastes. The method involves decomposition of organic substances by ozonation, preconcentration of elements to be determined by coprecipitation with thionalide at pH 9 or sorption on Dowes 1×2 loaded with 8-hydroxyquinoline-5-sulfonic acid at pH 7, irradiation of the concentrate, radiochemical separation of the respective radioisotopes and gamma spectrometric measurement of the activity. Accuracy and precision of the determination have been evaluated.     

Neutron activation analysis of microgram amounts of thorium in uranium ores and process liquors by means of thorium-233

A method is described for neutron activation analysis of thorium by employing thorium-233. Decontamination steps include anion exchange in 12.5 N HCL, precipitation of fluoride, extraction with mesityl oxide and thorium oxalate precipitation. The time spent is less than 1 h; spurious activities in counting samples amount only to 2% and can easily be corrected for. The sensitivity of the method is ca. 0.02 μg of thorium in a neutron flux of 10¹²n/cm²/sec with an irradiation time of 5 min.     

81mSe tracer for determination of the chemical yield in radiochemical neutron activation analysis of selenium

A radiotracer method is described for measurement of the chemical yield in radiochemical neutron activation analysis of selenium using the⁷⁵Se (120 d) induced nuclide. It is based on^81mSe (57 min) radioisotopic tracer, prepared immediately before its use in the radiochemical separation procedure, by neutron irradiation of highly enriched⁸⁰Se. The recovery of selenium is calculated from the 103 keV -peak of^81mSe in the separated selenium fraction used for quantitation of⁷⁵Se. The technique is illustrated by results for biological reference materials of good accuracy and reproducibility.     

Determination of lanthanum in large steel samples by the neutron activation method

In view of the inhomogeneous distribution of lanthanum in steel, large samples should be used for the determination of this element. The method elaborated consists in the preparation of an average samople by dissolving 50 g steel and analysing an aliquot of the obtained solution corresponding to 0.5 g of steel. In order to reduce the activity of the sample, iron and some other elements are separated from the steel solution by electrolysis prior to irradiation. The amount of lanthanum contamination introduced during the pre-irradiation treatment of the sample is relatively low (10^?10–10^?9 g) if the treatment is carried out under suitable conditions. The post-irradiation treatment consists in the separation of²⁴Na by shaking the sample solution with Sb₂O₅. The¹⁴⁰La-activity is measured by means of a γ-spectrometer (1.6 MeV photopeak).     

Neutron activation analysis of the peptides of thyroglobulin

Summary The peptides of thyroglobulin obtained by enzymatic hydrolysis with pronase and by two-dimensional paper chromatography have been investigated by neutron activation analysis in order to determine the micro amounts of iodine in each peptide. The greatest amount of iodine is present in the 2nd, 7th, 12th, 13th, 14th, and 15th peptides. The bulk of the iodine is present in the 14th and 15th peptides, which contain 17.7 and 34.3%, respectively, of the total iodine. There is a definite direct correlation between the concentrations of iodine in them.DeceasedMoscow Scientific-Research X-Radiographic Institute, Ministry of Health of the RSFSR. Institute of Nuclear Physics, Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 37–41, January–February, 1975.     

Neutron activation analysis for measuring the unsaturation in edible oils

Oil smears /2–10 mg/ on a filter paper were directly brominated by bromine vapor, and the quantity of Br reacted with the lipid was determined by instrumental neutron activation analysis. The iodine value for commercially available almond oil, sunflower oil, peanut oil, soy oil and sesame oil were determined by the proposed method. The relative standard deviation associated with the measurements was less than 3%. No significant difference was observed between the iodine values determined by the proposed method and that determined by one of the officially approved methods. The proposed method possesses the advantages of shortening reaction time and applicability to small sample size.