Semi-automated determination of iodine in biological fluids by activation analysis

A simple automated system has been built that permits the selective separation of radioiodine by ion-exchange in eight samples simultaneously and the regeneration of the resin columns in fifteen minutes. Iodine is subsequently determined by γ-spectrometry.     

Neutron activation method for nitrogen determination in biological specimens

For the determination of the nitrogen content in plants, 14 MeV neutron activation analysis was used based on the determination of the elemental concentration by measuring the area of the gamma-radiation of the radionuclide¹³N as a result of¹⁴N(n, 2n)¹³N reaction. Three methods were tested in order to obtain quantitative results: comparator method, method for absolute determination of the neutron flux and monitor method. Using the monitor method, results for nitrogen content in plant species were obtained-for beans 74.8% and for maize 1.8%. The precision of determination is ±10%. The possible sources of errors are analyzed. The efficiency of the Ge(Li) detector has been determined using a combined -source in the energy interval 120–1400 keV with precision of 4.5%. The sensitivity achieved was 4 mg or 47 imp/mg per min.     

Neutron activation analysis of manganese in biological samples

The ordinary histopathological technique utilizing an automatic tissue processor was studied to remove interfering elements of sodium and chlorine so that nondestructive neutron activation analysis of tissue could be accomplished. The manganese values obtained by this method were found to compare favorably with other methods. Deceased.     

Neutron activation analysis of the inorganic ions in Langmuir-Blodgett multilayers

An application of neutron activation analysis for the determination of inorganic ions in Langmuir—Blodgett multilayers is described. A special technique for the removal of multilayers from the solids substrate has been used. Multilayers of arachidic acid and octadecylamine are analyzed with respect to Cd²⁺ and HPO ₄ ²⁻ . Ca²⁺, Ba²⁺, Cu²⁺, HAsO ₄ ²⁻ , Cro ₄ ²⁻ and other ions can also be determined by means of this method. The results obtained are compared with those of other authors.     

Neutron activation analysis for the determination of contaminants in food contact materials

A neutron activation method has been developed for the analysis of high density polyethylene, low density polyethylene, polypropylene, polyethylene terephthalate and polystyrene. Samples weighing 2–5 g were irradiated in a thermal neutron flux of 10¹⁶ neutrons m^–2 s^–1 and measured with gamma ray spectrometry for 64 elements. With the method developed here over 50 elements can be detected at concentrations below 1 mg/kg. Correction factors were applied for neutron flux variation and counting geometry.The method was validated using reference material citrus leaves (NIST) for Na, Mg, Al, K, Ca, Mn, Cu, Sr and I, and a suite of in house standards doped with Al, Cr, Co, Mg, Zn and Sb confirmed repeatability of the method. The method was used to measure inorganic contaminants in the raw polymers and retail samples of plastic packaging used in contact with food.     

Neutron activation analysis of biological materials by the monostandard method

Instrumental neutron activation analysis by the monostandard method has been applied to the analyses of biological NBS standard reference materials; 1571 Orchard Leaves and 1577 Bovine Liver. Aluminum foils containing 0.100% gold or 2.00% cobalt were used as the monostandards. The gamma-ray spectral data were recorded on punched paper tape and were analyzed by a computer assisted data processing. The following 25 elements were determined: Al, Ca, Cl Cu, Mg, Mn, V (by short period irradiation), As, Ba, Br, Co, Cr, Cs, Eu, Fe, Hg, K, La, Na, Rb, Sb, Sc, Se, Sm and Zn (by long period irradiation). The results were compared with the certified values by NBS and the reported values in literatures to prove the reliability and accuracy of the monostandard method.     

Neutron activation analysis of the process of metal gettering in silicon slices

Neutron activation analysis is used to study the process of Cu gettering in a silicon wafer in which differently doped and disordered regions are present. The results show a strong preference of the copper atoms to be concentrated in the n⁺(p⁺) and in the n⁺ regions. The effectivity of the gettering process can be increased by thermal growth of the defects present in the boron implanted layers.     

Neutron activation analysis for determination of induced radioactivity in concrete of nuclear reactor shielding

The content of binding agent components and aggregates of shielding concrete (portland cement, gabbro, silicate, granite, hematite, magnetite, limestone) has been studied to identify nuclides contributing to the long-lived radioactivity of concretes used in nuclear reactor shielding. Elemental content was determined by neutron activation analysis at the IBR-2 reactor of the Laboratory of Neutron Physics (JINR). It is shown that the nuclides mainly responsible for the long-lived activity are¹⁵²Eu,¹⁵⁴Eu,⁶⁰Co and¹³⁴Cs. Based upon the experimental data obtained, calculations of the specific activity of concrete ingredients being irradiated for 30 years by a unit neutron flux density have been performed, and diagrams of the dependence of the specific activity versus time are presented. It is recommended that the application of such media as magnetite, serpentinite, chromite to shielding structures should be abandoned. Estimations of the dose rate from concrete structures containing various aggregates for the limiting case of semi-infinite space are given. The results obtained can form the basis for the optimal choice of the materials when constructing the concrete shielding of neutron sources.     

A study of the iodinated resin column for the determination of iodine in biological fluids by radiochemical neutron activation analysis

The iodinated resin technique for separation of¹²⁸I directly from neutron irradiated biological fluids is attractive due to its rapidity, simplicity and high degree of radiochemical purity; however, some doubts exist about the yields of iodine which can be recovered, particularly from organically bound iodine. In the present study, chemical yields on the resin column were studied for irradiated urine, serum and milk by standard additions of iodide and thyroxine. It was found that yields are not quantitative but lie in the range 80–95%, depending on the matrix, with a variability of up to 6% standard deviation. In addition it was shown that no significant adsorption of iodine occurs on polythene ampoules from irradiated biological fluids of natural pH. Some comparative experiments between the resin technique and the oxygen flask ignition method on fluids before or after drying, respectively, showed satisfactory agreement. It is concluded that the iodinated resin technique is suitable for routine analyses or large scale screening programs.Presented in part at SAC 83, Edinburgh, July 1983.     

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.     

Kinetic determination of creatinine in biological fluids by stopped-flow injection analysis

Summary A kinetic photometric method for the determination of creatinine in biological fluids based on the Jaffé reaction and the use of a flow injection manifold where the reacting plug is halted prior to detection is proposed. The wide linear range of the calibration curve obtained (between 3 and 150 g ml^–1) allows the determination of the analyte in serum and urine. The kinetic measurements require no sample pretreatment (urine samples need dilution). The proposed method compares favourably with the standard recommended procedure.     

Neutron activation determination of impurities in germanium

A neutron activation (NA) method for the determination of 24 microimpurities in germanium has been developed. The method is based on the separation of the matrix and isotopes genetically connected by extraction chromatography.     

Neutron activation analysis after a nickel sulphide fire assay preconcentration for determination of all platinum group elements in rocks

Neutron activation analysis after a nickel sulphide fire assay preconcentration for platinum group elements (PGE) has been established in our laboratory. In this work, the all PGE in DZ-2, a Chinese certified ultramafic rock standard reference material, are determined for testing the accuracy and precision of the method. The experimental conditions and the blank values from reagents and detection limits for the method are also presented.     

Neutron activation analysis as a tool for checking the reliability of spectrophotometric methods for the determination of molybdenum and tungsten in biological materials

A new method for the simultaneous determination of molybdenum and tungsten in biological materials by neutron activation analysis has been developed. It involves a single step radiochemical separation of both elements by extraction chromatography using -benzoinoxime supported on Bio-Beads SM 2. Good accuracy and precision of the method was demonstrated analyzing Bowen's Kale and IAEA's H-8 /Horse Kidney/ reference materials. The method was applied to check the reliability of the results obtained by one standard and one newly developed spectrophotometric methods for the molybdenum content in some plant materials.     

Neutron activation analysis method for the determination of neptunium in sub-microgram quantities in process solutions

A neutron activation analysis method, for the estimation of sub-microgram level²³⁷Np present in process solutions of a fuel reprocessing plant is described.     

Spectrophotometric determination of proteins in biological fluids

A comparative analysis of procedures of the spectrophotometric determination of total protein with various organic dyes, Bromocresol Green, Bromophenol Blue, and Pyrogallol Red, in biological fluids is presented. It is shown that the results of determination with various dyes can differ because of the specific features of reagent interaction with the components of biological fluids. A new organic reagent, Bromopyrogallol Red, possessing equal sensitivity to different protein fractions (albumins and globulins) and ensuring a minimum error of the determination of total protein in clinical examinations using calibration solutions of various compositions is proposed. A procedure for the determination of total protein in biological fluids is developed and tested on real samples of urine and blood serum.     

Spectrofluorimetric determination of proguanil in biological fluids

A spectrofluorimetric method for proguanil in biological fluids is described based on the reaction of proguanil with 9-fluorenecarboxylic acid chloride and measurement of the resulting s-triazine derivative. The limits of detection for proguanil in methanol, water, plasma, urine and saliva are 1.5, 5.1, 7.6, 4.2 and 11.9 ng ml^?1, respectively. Preliminary results for proguanil levels in plasma and saliva following a single 100-mg oral dose are reported.     

A micromethod for the determination of metal ions in biological tissues by furnace atomic absorption spectrophotometry

A method was developed for determination of metals in samples of some few micrograms in weight. Samples were wet-oxidized in small test tubes and an aliquot of the sample was automatically injected in a carbon-rod atomizer. Precision and recovery was good for the analytical procedure. Application of the method to analysis of soil invertebrates showed a considerable variation in metal concentration between individuals from the same habitat.     

Neutron activation determination of noble metals for the analysis of technological and natural materials

Two previously developed methods of noble metal neutron activation (NA) determination have been applied for the analysis of technological materials. While comparing the data obtained by both methods with those obtained in Central Chemical Laboratory the systematical discreapences have been shown to be absent. A new method of Pd, Au, Pt and Ir NA determination in natural and technological specimens based on the selective extraction of Pd and Au preliminary to irradiation has been developed. Results of the analysis of “Glomar Cellenger”'s deep-water drilling samples are discussed obtained by this method.