Determination of phosphorus in polymers by INAA

An INAA technique employing beta spectrometry was developed for the determination of phosphorus in polymers. The (n,γ) reaction on phosphorus produces³²P, half-life 14.3 days, a pure beta emitter with end-point energy 1.71 MeV. Polymer samples in the form of powders, films and pellets are irradiated and then counted with a plastic scintillator. The beta spectrum is corrected for interferences (especially Sb, Zn and Br which are quantified by gamma spectrometry) and for energy loss in the thick sample. Samples must also be analyzed for S and Cl which cause nuclear interferences. With an irradiation time of 4 hours at a neutron flux of 5·10¹¹ n·cm^{−2 s −1}, decay time 10 days and counting time 10 minutes, the sensitivity is 520 counts/μg phosphorus and the detection limit is typically 2μg/g.     

Instrumental activation analysis for determining the composition of micro-ingots of multi-constituent alloys

A procedure for the instrumental neutron activation analysis of micro-ingots of alloys containing In, Sb, Au, Ga, Ni, Sn and Bi is proposed. The non-destructive analysis of the irradiated samples is performed by γ-spectrometry techniques including one-crystal scintillation detectors, dual-crystal sum-coincidence scintillation detectors and Ge(Li) semiconductor detectors. As a result, the cumbersome operations of radiochemical separation can be eliminated. The sensitivity of quantitative determinations using scintillation detectors in alloys of the above composition is 10⁻¹⁰ g for indium, gold, antimony and gallium and 10⁻⁶ g for nickel and tin. The use of semiconductor detectors yields sensitivities of 10⁻¹⁰ g for indium and gold and 10⁻⁹ g for gallium and antimony.     

Alternative chromatographic processes for no-carrier added 177Lu radioisotope separation Part I. Multi-column chromatographic process for clinically applicable

The conventional multi-column solid phase extraction (SPE) chromatography technique using di-(2-ethylhexyl)orthophosphoric acid (HDEHP) impregnated OASIS-HLB sorbent based SPE resins (OASIS-HDEHP) was developed for the separation of no-carrier added (n.c.a) ¹⁷⁷Lu from the bulk quantity of ytterbium target. This technique exploited the large variation of lutetium metal ion distribution coefficients in the varying acidity of the HCl solution-OASIS-HDEHP resin systems for the consecutive loading-eluting cycles performed on different columns. The production batches of several hundred mCi n.c.a ¹⁷⁷Lu radioisotope separated from 50 mg Yb target activated in a nuclear reactor of medium neutron flux (Φ = 5·10¹³ n·cm⁻²·s⁻¹) were successfully performed using the above mentioned separation technique. With the target irradiation in a reactor of thermal neutron flux Φ = 2·10¹⁴ n·cm⁻²·s⁻¹ or the parallel run of several separation units, many Ci-s of n.c.a ¹⁷⁷Lu can be profitably produced. The OASIS-HDEHP resin based multi-column SPE chromatography technique makes the separation process simple and economic and offers an automation capability for operation in highly radioactive hazardous environments.     

Determination of trace impurities in tin by neutron activation analysis

Two methods are described to determine indium and managenese in high-purity tin. In the first method indium and manganese are separated from the tin and antimony matrix activities on Dowex 1X8 anion exchanger. Tin and antimony are adsorbed in 10M HF while indium and manganese are eluted. In the second method the incident γ-ray intensity due to the tin matrix is reduced by placing a lead absorber between the sample and the detector. The reproducibility and the sensitivity of both methods are of the order of 10 ppb for manganese and of 1 ppb for indium for 1 g samples and a neutron flux of 10¹¹ n·cm⁻²·sec⁻¹. Aspirant of the N. F. W. O.     

Measurement of alpha-decay constant to fission cross section ratio for actinides using solid state nuclear track detectors

A simple technique based on the measurement of the ratio of alpha-decay constant to neutron induced fission cross section for pure actinides using solid state nuclear track detectors (SSNTDs) is developed for the identification of the actinides in trace levels in pure solutions. The alpha-decay constant to fission cross section ratios for depleted U,²³⁸Pu and²⁴⁰Pu have been measured for the epicadmium neutron induced fission of these actinides. The measured values are (6.19±0.34)·10⁶, (6.95±0.26)·10¹², (2.12±0.95)·10⁹ and (2.18±1.58)·10¹¹ sec⁻¹·cm⁻², respectively. These ratios can be used for the trace level identification of pure actinides.     

Determination of metals in alloys by neutron capture gamma-ray spectrometry

A collimated neutron beam capable of providing a thermal neutron flux of 4.75·10⁷ n·cm⁻²·sec⁻¹ has been used to analyze alloy samples of 1–5 g during relatively short irradiation times of 30 min by the use of neutron capture gamma-ray spectrometry. The analyses were performed by using a mathematical treatment that relates the count ratio of every constituent present in the matrix with the concentration and thus it requires no standards. The technique was applied to the analysis of steel and gold alloy samples. Errors ranged from 0.8%–10%.     

Multi-element analysis of biological samples after intense neutron irradiation an fast chemical separation

For the simultaneous determination of many elements in small biological samples, a multi-element analysis has been developed using neutron activation. After a 24-hr irradiation in a neutron flux of 2.5·10¹⁴ n·cm⁻²·sec⁻¹ and after immediate chemical separation without cooling, it was possible to analyse 24 elements in bovine liver (NBS-SRM 1577). The separation apparatus, set up in a shielded cell can work four samples simultaneously, and its operation is fast enough to allow the detection of radioisotopes with a half-life of about 2 hrs (¹⁶⁵Dy,^57mSr,⁵⁶Mn). Amounts lower than 10⁻³ μg of Dy, Eu, Pr, Sm and Yb were determined.     

Investigation of the interaction of Greek dolomitic marble with metal aqueous solutions using rutherford backscattering and X-ray photoelectron spectroscopy

To enhance the applicability of the nuclear analytical technique in the field of industry and the environment, the inorganic elemental content of the bottom ash from a municipal solid waste incinerator was determined by instrumental neutron activation analysis. Bottom ash samples were monthly collected from an incinerator located at a metropolitan city in Korea, strained through a 5 mm sieve, dried by an oven and pulverized by an agate mortar. The samples were irradiated at the NAA #1 irradiation hole (thermal neutron flux: 2.92·10¹³ n·cm⁻²·s⁻¹) in the HANARO research reactor of the Korea Atomic Energy Research Institute and the irradiated samples were measured by a HP Ge gamma-ray spectrometer. Thirty-three elements including As, Cr, Cu, Fe, Mn, Sb and Zn were analyzed by an absolute method. The quality control was conducted by a simultaneous analysis with NIST standard reference materials. The average concentrations of the major elements such as Ca, Fe, Al, Na, Mg, K and Ti measured in the sample were 19.9%, 4.85%, 3.79%, 2.11%, 1.84%, 1.22% and 1.02%, respectively. In addition, the concentrations of the hazardous metals like Zn, Cu, Cr, Sb and As were 0.77%, 0.31%, 729 mg·kg⁻¹, 116 mg·kg⁻¹ and 22.2 mg·kg⁻¹, respectively.     

Neutron activation analysis of uranium in human bone,drinking water and daily diet

Uranium in human bone, drinking water and daily diet has been determined by neutron activation analysis using the²³⁸U(n, γ)²³⁹U reaction. An improved scheme for the separation of the²³⁹U is proposed; with this scheme, after neutron irradiation in a 100 kW TRIGA reactor, a uranium content as low as 5·10⁻¹¹ g can be determined reliably, rapidly and easily. A wide range of uranium concentrations, from about 0.1 ppb up to about 10 ppb has been found in the bones of normal Japanese. Water from several Japanese city water services, and the daily diet taken in two Japanese cities, have been found to contain an average 9·10⁻⁹ g/l and 1.5 μg per person-day uranium, respectively.     

The estimation of barium in biological material by neutron activation analysis

Barium is estimated in biological material by thermal neutron activation analysis and measurement of¹³⁹Ba by γ-counting. The biological material is digested with nitric acid and scavenged with ferric hydroxide. A special fluoride precipitation removes calcium and strontium and the barium is recovered as the chromate. The method allows the analysis of up to 40 samples per day and the sensitivity is 0.1 μg after irradiation for 85 mins at 4·10¹²n·cm⁻²·sec⁻¹.     

Neutron activation analysis of Bawachi seeds

Seeds of (the plant) P. Corylifolia Linn (Bawachi) known for their therepeutic value in indigenous medicine have been analysed for Cu, As, Sb and Se by thermal neutron activation analysis involving substoichiometric extraction and precipitation technique. The amounts of Cu, As, Sb and Se per gram of seeds dried at 80°C are 16.0±1.1 μg, 0.90±0.4 μg, 12.1±0.6 μg and 4.0±0.2 μg respectively.     

Determination of chromium in blood by neutron activation analysis

A procedure for the determination of chromium in blood has been developed with a sensitivity of 5×10⁻³ μg Cr. Dried blood was irradiated with a neutron flux of 10¹² n·cm⁻²·sec⁻¹ in the VVRS reactor for 4 weeks, then the sample was mineralized and the chromium isolated by extraction as perchromic acid. The determination of the chromium content was accomplished by measuring the 0.32 MeV gamma energy of⁵¹Cr. In order to make correction for the interfering reaction⁵⁴Fe(n,α)⁵¹Cr, the formation of chromium from high-purity iron was investigated. The chromium content of the blood samples was between 1.03×10⁻² and 5.2×10⁻² ppm Cr.     

Speciation analysis of inorganic antimony in soil using HPLC-ID-ICP-MS

Speciation analysis of Sb(III) and Sb(V) in a soil sample was performed through extraction and on-line isotope dilution concentration determination after a chromatographic separation. The total Sb concentration found in a through traffic contaminated soil sample was (4.17 μg g⁻¹, 0.3 μg g⁻¹ SD, n=6). It was determined using ICP-MS after soil digestion using the sodium peroxide sintering method. The optimized extraction procedure for speciation analysis was carried out using 100 mmol L⁻¹ citric acid at pH 2.08 by applying an ultrasonic bath for 45 min at room temperature. The effects of citric acid concentration (0–500 mmol L⁻¹), pH (1–6), and temperature (30–60°C) on inorganic antimony species distribution in the examined sample were studied and optimized. The separation of Sb(III) and Sb(V) was achieved using an anion exchange column (PRP-X100) and 10 mmol L⁻¹ EDTA and 1 mmol L⁻¹ phthalic acid at pH 4.5 as a mobile phase. The eluent from the HPLC was mixed with an enriched (94.2%) ¹²³Sb spike solution that was pumped by a peristaltic pump with a constant flow rate (0.5 mL min⁻¹) in a three-way valve. The blend passed directly to the Conikal nebulizer of the ICP-MS. By using the above extraction procedure and methodology, 43.2% Sb(V) (2.9% RSD, n=3) and 6.0% Sb(III) (1.3% RSD, n=3) of total Sb found in the sample could be detected. The detection limits achieved by the proposed method were 20 ng L⁻¹ and 65 ng L⁻¹ for Sb(V) and Sb(III), respectively. The precision, evaluated by using RSD with 100 ng L⁻¹ calibration solutions, was 2.7% and 3.2% (n=6) for Sb(V) and Sb(III), respectively, in aqueous solutions.     

A simple spectrophotometric procedure for the determination of antimony (III) and (V) in antileishmanial drugs

A spectrophotometric method for the selective determination of antimony (III) and (V) in antileishmanial drugs is described. The procedure is based on the reaction of Sb(III) with bromopyrogallol red (BPR) in neutral solution. As a consequence of the Sb-BPR complex formed, the absorbance of BPR, at 560 nm, decreases proportionally to the amount of Sb(III) in the analyte solution. The calculated apparent molar absorptivity and determination limits are 3.67 × 10⁴ L · cm^–1 · mol^–1 and 1.65 × 10^–6 mol/L, respectively. Sb(V) is determined after reduction to Sb(III) by iodide. The Sb(V) content determined in ten samples of Glucantime varied from 75.40 ± 0.97 to 94.47 ± 1.0 mg/mL. Sb(III) was detected in all samples analyzed, and mean values ranged from 5.19 ± 0.16 to 10.52 ± 0.15 mg/mL. The method is suitable for the routine quality control of pharmaceutical formulations. Received: 26 July 1996 / Revised: 17 October 1996 / Accepted: 11 December 1996     

Halogen speciation in the rat thyroid: Simultaneous determination of bromine and iodine by short-term INAA

The study describes a mode of non-destructive simultaneous determination of bromine and iodine concentrations, by reactor instrumental neutron activation analysis (INAA) in the regime of short-term activation. Under the conditions of 1-minute activation in the neutron flux of 8.0·10¹³ n·cm⁻²·s⁻¹, it was possible to determine reliably as little as 5·10⁻⁸ g bromine and about 10⁻⁷ g iodine in matrices of a given type and of the mass of about 5 mg dry weight. We applied this method for the determination of Br and I concentrations in the whole rat thyroid gland as well as for the halogen speciation in fractions separated from this organ.     

Application of fission track registration technique in the estimation of fissile materials

Analysis of fissile materials in solution by fission track registration technique has been extended to plutonium in solution of its alloys. In these estimations, the results agreed within 1–4% with the average of those obtained by other chemical and instrumental methods like potentiometry, mass-spectrometry and X-ray fluorescence. Some special practical problems encountered in the analysis of plutonium solutions are noted. Various factors affecting the results have been investigated and the necessary precautions for reducing these errors have been indicated. The advantages of the method over some other conventional methods have also been discussed. It is suggested that a source of about 10 μg of²⁵²Cf corresponding to a neutron flux of about 10⁷ n·cm⁻²·sec⁻¹ is ideal for these experiments.     

Determination of vanadium in human serum by neutron activation analysis

Vanadium in serum has been investigated by the aid of neutron activation analysis (8 min irradiation at 8·10¹³ n·cm⁻²·s⁻¹ in the reactor FR-II of the Kernforschungszentrum in Karlsruhe). The lyophilized samples were dry-ashed before irradiation and the⁵²V activity extracted after irradiation. The values for V in the sera of 22 healthy males ranged from 0.029–0.939 ng V·ml⁻¹. There is a real assumption that some of the high figures are due to persons being contaminated with V. The 18 healthy females yielded a mean value of 0.033±0.012 ng V·ml⁻¹ for 17 of them and one additional value of 0.139 ng V·ml⁻¹. These V-data are the lowest ever reported in the literature. The analyses of two packed blood cell samples yielded 0.031 and 0.020 ng·g⁻¹, indicating that about 68% of the total V in blood is present in serum. There was no correlation between the V-content and age, nor between the V-content and the cholesterol, triglycerides or the lipoprotein fractions in serum.     

Determination of nanogram quantities of gold in biological tissues by nondestructive neutron activation analysis

We describe a method for gold analysis in kidney and liver. The technique is simpler than other methods in that it does not require ashing or acid digestion of the sample. The tissue is dried, placed into a polyethylene vial and diluted with a 2 ml sodium chloride solution. Gold concentration is determined by neutron activation analysis. Samples are irradiated for two hours at a thermal neutron flux of 10¹²n·cm⁻²·s⁻¹ and are then allowed to decay for 3–4 days before counting. The detection limit (20 ng Au/ml) and precision (±6.1%) permits the accurate analysis of gold in these tissues. This technique could aid in a re-examination of gold metabolism.     

Dosage non destructif de l’hafnium par activation neutronique et spectrometrie γ de179mHf et de178mHf (periodes respectives: 19.0 et 4.8 s)

A non-destructive method for the determination of hafnium in zirconium and various alloys, based on the formation of^178mHf and^179mHf, is proposed. For a neutron flux of 10⁹ n _th ·cm⁻²·sec⁻¹, the limit of determination is about 0.5 μg. This limit can fall to 50 ng with the multiple irradiation runs system (ten runs at 92-second cycles). The simple determination is complete within 15 minutes, whereas the multiple irradiation runs method requires about 15 minutes longer time.      

Lower limit of determination values for trace elements in iron certified reference materials by neutron activation analysis with multiple gamma-ray detection

Recycling steel products demands a new technique for determining tramp elements in steel. Tramp elements, As and Sb, in some iron certified reference materials were determined by neutron activation analysis with multiple gamma-ray detection method and reported in MTAA11. In MTAA12, the authors reported the lower limit of determination values (LDL) and the dispersion of this method. The values of the LDLs for As and Sb in high purity iron were 0.002 and 0.0009 μg·g⁻¹. The dispersion is small enough to satisfy the demand from materials science.