Precise determination of macro contents of nitrogen in titanium carbonitride by instrumental photon activation analysis

SYNTH, a Windows^TM based software package developed for generating synthetic gamma-ray spectra, has been updated and extended to include the ability to generate gamma-ray spectra resulting from neutron activation. Along with a new gamma-ray library (based on the NNDC PCNuDat compilation), and the best available neutron cross-sections, it is now possible to simply, and quickly predict the interference effects of different bulk and trace element compositions by generating a synthetic gamma-ray spectrum that will be representative of a specific set of input parameters. The parameters include, but are not limited to: elemental composition (bulk, and trace) of the sample; irradiation, decay, and count times; thermal, and resonance neutron flux; sample to detector distance; detector specifications; and electronics configuration. Using existing data reduction codes, it is then possible to generate Minimum Detectable Activities (MDA's) for other trace elements that you may wish to detect in this type of matrix.     

The instrumental analysis of inactive tracers by photon activation

Because of incresing problems due to the general non-acceptance of the application of open radioactivity in modern industrial research an investigation was made concerning the possibility of replacing radiotracers by inactive substances activated by photons after sampling. As an example, investigations in the glass-processing industry was selected. The results were confirmed by the radiotracer experiment performed in parallel. The data obtained were in good agreement.     

Determination of the elemental contents in stream sediments collected from Cheongju city by instrumental neutron activation analysis

Sediment samples were collected from seven locations of the MeeHo stream in Cheongju city, strained out by a sieve, dried by an oven and pulverized by an agate mortar. Instrumental neutron activation analysis (INAA) was applied for the determination of the elemental contents in the sediment samples by using the NAA #1 and #2 irradiation holes of the HANARO research reactor and HPGe gamma-ray spectrometers. Twenty-five elements were determined by a relative method with NIST SRM 2711-Montan Soil and the ranges of the elemental contents for the seven locations were identified. The contamination levels for elements such as As, Ba, Cr, Mn, Fe and Zn were compared with the guidelines of USEPA. The detection limits and combined uncertainties for the hazardous elements such as As, Ba, Cr, Mn, Sb, V and Zn were estimated under the given analytical conditions.     

Accurate measurement of bromine contents in plastic samples by instrumental neutron activation analysis

Accurate measurements of bromine contents in plastic samples were made by the direct comparator instrumental neutron activation analysis (INAA). Individual factors affecting the measurements were comprehensively evaluated and compensated, including the volatility loss of bromine from standard comparators, the background bromine level in the filter papers used for preparation of the standard comparators, nuclear interference, γ-ray spectral interference and the variance among replicates of the samples. Uncertainty contributions from those factors were thoroughly evaluated and included in the uncertainty budgeting of the INAA measurement. ⁸¹Br was chosen as the target isotope, and the INAA measurements for bromine were experimentally confirmed to exhibit good linearity within a bromine content range of 10–170 μg. The established method has been applied to the analysis of eight plastic samples: four commercially available certified reference materials (CRMs) of polyethylene and polystyrene and four acrylonitrile butadiene styrene (ABS) samples prepared as the candidate reference materials (KRISS CRM 113-01-012, -013, -014 and -015). The bromine contents of the samples were calculated at three different γ-ray energies and compared, showing good agreement. The results of the four CRMs also showed good consistency with their certified values within the stated uncertainties. Finally, the bromine contents of the ABS samples were determined with expanded uncertainties (at a 95% level of confidence) between 2.5% and 5% in a bromine content range of 25–900 mg kg⁻¹.     

The determination of some elements in rocks by instrumental photon activation analysis

This text describes the instrumental determination of some elements in silicate samples of ≃1 g by photon activation. The following elements can be determined: In acidic rocks: Mg, Ca, Ti, Mn, Sr, Zr and Nb, in ultramafic rocks: Mg, Cr, Ni, and Mn. The relative standard deviation is a few percent.     

Multi-element determinations of trace elements in glass by instrumental photon activation analysis

An instrumental photon activation method is reported for multi-element determinations in glass. The concentrations of 17 elements in NBS standard glass can be determined by irradiation with 30-MeV bremsstrahlung and measurement of the resulting γ-rays with a Ge(Li) detector. The average of all relative standard deviations is 2.7%; the relative deviations from the NBS certified values range from 1.4 to 3.4%.     

Application of instrumental neutron activation analysis to ceramic solid electrolytes

Beta" alumina isomorphs with different conducting cations were produced by ion exchange in molten salts. The concentration of the main component (Al), of conducting ions (Na⁺, Sr⁺⁺, Ba⁺⁺) and of chlorides from residues of the melt inside the exchanged material was determined by instrumental neutron activation analysis (INAA).Dedicated to Professor Günther Tölg on the occasion of his 60th birthday     

Determination of lithium by instrumental neutron activation analysis

The fast transfer system in the DR 2 reactor for irradiation at a thermal neutron flux density of 10¹³ n·cm⁻²·sec⁻¹ was used for the determination of lithium by the⁷Li(n, γ)⁸Li reaction. β-counting with a large perspex Cerenkov detector begun at 0.3 s after the end of irradiation, and multi-scaler data was accumulated in 300 channels at 0.1 s per channel. With a suitable choice of discrimination level only¹⁶N and background interfere, and the 0.84 s half-life of⁸Li was resolved by the method of weighted least squares. Results are presented for 36 international geochemical reference materials, and for a few biological samples, including BOWEN's kale and the NBS Standard Reference Material 1571 Orchard Leaves.     

Oxygen and nitrogen in coal by instrumental neutron activation analysis

The feasibility of using fast neutron (14 MeV) activation analysis techniques for the determination of oxygen and nitrogen in coal has been investigated. Conditions that favor instrumental neutron activation analysis (INAA) include the absence of problems associated with sample dissolution and the capability of extremely rapid analyses as compared to older techniques such as the Kjeldahl method for nitrogen. Most previous oxygen determinations have been by difference after major component analyses. In the present study, oxygen was determined in sized coal and its low temperature ash (LTA) with the difference representing the organic oxygen content. Both the oxygen and nitrogen analyses employ a multiscaling technique with the former based on the¹⁶O(n, p)¹⁶N reaction, while the latter utilizes the annihilation radiation produced by the product of the¹⁴N(n, 2n)¹³N reaction. The high-energy gamma-radiation associated with the decay of¹⁶N was essentially free of spectral interferences for coal analysis, although fluorine could cause a primary interference if the F/O ratio exceeds 0.02. In the nitrogen work, experiments were performed to determine correction factors to account for the effects of the¹²C(p, γ)¹³N and¹³C(p, n)¹³N “knock-on” reactions and the³⁹K(n, 2n)³⁸K reaction which produce interfering β⁺ emitting radionuclides. Data are presented for oxygen in Western Kentucky No. 9 and No. 11 coal and coal ash and for nitrogen in eleven different coals.     

Elemental analysis of traditional medicinal seeds by instrumental neutron activation analysis

Traditional medicinal seeds prescribed for specific treatment purposes, were purchased from local markets and analyzed by INAA. The samples were irradiated at Es-Salam research reactor, at a power of 5 MW for 6 h. The accuracy of the method was established by analyzing reference materials. Twenty elements were measured, with good accuracy and reproducibility. The concentration of elements determined, was found to vary depending on the seeds. The daily intake of essential and toxic elements was determined, and compared with the recommended values. The probable cumulative intake of toxic elements is well below the tolerance limits.     

Determination of nitrogen and fluorine in air-dust samples by photon activation

Summary Air-dust samples with masses of 12 mg each were analysed instrumentally for their nitrogen and fluorine content by photon activation. The samples were irradiated with photons of maximum energy,E _max=15MeV. The nuclear reactions¹⁴N(, n)¹³N and¹⁹F(, n)¹⁸F give two positron emitters. The positrons react with electrons, emitting annihilation radiation. The 511-keV peak of the annihilation radiation of¹³N and¹⁸F is measured simultaneously and the decay curve is taken. The half-lives of 9.96 and 109.7 min allow a quantitative separation. By choosingE _max=15 MeV for the activation we eliminate interference from carbon and oxygen. The activation threshold for the n,-reaction of carbon is 18.72 MeV and for oxygen 15.67 MeV, while the activation threshold for N is 10.55 MeV and for F 10.44 MeV. The detection limit for the instrumental method is 4g for both nitrogen and fluorine.

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Die Analyse von Stickstoff und fluor in Luftstaubproben durch Photonenaktivierung

Zusammenfassung An Luftstaubproben von 12 mg Masse konnte der Gehalt an Stickstoff und Fluor durch Photonenaktivierung zerstörungsfrei bestimmt werden. Die Proben wurden mit Photonen einer Energie von E_max=15 MeV bestrahlt. Die 511-keV-Linie der nach¹⁴N (, n)¹³N und¹⁹F (, n)¹⁸F entstandenen Nuklide wurde simultan gemessen und die Zerfallskurve aufgenommen. Die Halbwertszeiten 9,96 und 109,7 min liegen so weit auseinander, daß eine quantitative Trennung möglich ist. Durch Wahl der Aktivierungsenergie treten keine Störungen durch Sauerstoff und Kohlenstoff auf, da die Aktivierungsschwellen für die, n-Reaktionen von C bei 18,72 MeV und von O bei 15,67 liegen, während sie für N bei 10,55 MeV und für F bei 10,44 MeV liegen. Die Nachweisgrenzen liegen beim zerstörungsfreien Verfahren bei 4g für N und für F.

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Presented at the 8th International Microchemical Symposium, Graz, August 25–30, 1980.     

Determination of nitrogen in solids by photon and reactor neutron activation

Carbon and nitrogen were determined in iron, steel, and silicon by photon activation followed by chemical separation. Nitrogen was determined in the same types of samples by reactor neutron activation, chemical separation, and liquid scintillation counting. The comparison of two methods based on different radioactive elements is a way to control the accuracy of the determination.     

Prompt gamma-ray neutron activation analysis methodology for determination of boron from trace to major contents

Prompt gamma ray neutron activation analysis methodologies were standardized using a reflected neutron beam and Compton suppressed γ-ray spectrometer to quantify boron from trace to major concentrations. Neutron self-shielding correction factors for higher boron contents (0.2–10 mg) in samples were obtained from the sensitivity of chlorine by irradiating KCl with and without boron. This method was validated by determining boron concentrations in six boron compounds and applied to three borosilicate glass samples with boron contents in the range of 1–10 mg. Low concentrations of boron (10–58 mg kg⁻¹) were also determined in two samples and five reference materials from NIST and IAEA.     

Determination of boron in the thin surface layer of a silicon wafer by instrumental charged particle activation analysis

Instrumental charged particle activation analysis (CPAA) for determining boron in a thin surface layer of silicon was developed. The nuclear reaction and incident energy were selected in order to minimize any interference from surface or bulk impurities. Thin boron film was used as a standard sample and its boron content was determined by neutron induced prompt -ray analysis. As a result, we were able to determine¹¹B and¹⁰B at 10¹⁵ atoms/cm² with an accuracy of better than 3% by 4 MeV proton and 7 MeV -bombardment, respectively. Each boron isotope could be determined down to 10¹³ atoms/cm². Our CPAA was applied to determine boron in a boron implanted silicon wafer of a SIMS standard sample.     

Determination of carbon in copper by photon activation analysis

Determination of carbon in copper has been studied by photon activation analysis using 30 MeV bremsstrahlung. Chemical separation of carbon as CO₂ was performed by the combustion method in a high flow rate of oxygen stream. It has been demonstrated that the trace amount of carbon in copper can be determined accurately and precisely, and that the detection limit is 0.02 g.     

Determination of aluminium in lutetium by instrumental neutron activation analysis

In lutetium metal 45 ppm aluminium have been determined by instrumental neutron activation analysis. Interference from the very intensive γ-radiation of^176mLu was eliminated by application of lead filters. The determination limit of the method was estimated to be 0.7 μg or 3 ppm Al.     

Determination of boron, carbon, nitrogen and oxygen in nickel by charged particle activation analysis

Summary The determination of boron, carbon, nitrogen and oxygen in nickel by charged particle activation using the reactions ¹⁰B(d, n)¹¹C, ¹²C(d, n)¹³N, ¹⁴N(p, )¹¹C and ¹⁶O(³He, p)¹⁸F is studied. The interference of ¹¹B(p, n)¹¹C with the ¹⁴N(p, )¹¹C reaction is taken into account. ¹¹C, ¹³N and ¹⁸F are separated by oxygen combustion followed by trapping of ¹¹CO₂ in NaOH and by steam distillation of ¹³NH₃ and of H₂Si¹⁸F₆, respectively. The results obtained were 0.129±0.035 g g^–1 for boron, 86.4±8.3 g g^–1 for carbon, 1.077±0.037 g g^–1 for nitrogen and 8.91±1.00 g g^–1 for oxygen. The results for nitrogen and oxygen agreed satisfactorily with those of other analytical methods.Grateful acknowledgement is made to Prof. J. Hoste for his interest shown in this work, to J. Pauwels (B.C.M.N., Geel) for providing the samples, to B. F. Schmitt (Bundesanstalt für Materialprüfung, Berlin) for helpful information concerning the radiochemical separation of ¹¹C and to the NFWO and the IIKW for financial support.     

Determination of fluorine in standard rocks by photon activation analysis

A highly sensitive determination of fluorine in standard rocks by photon activation using the¹⁹F(,n)¹⁸F reaction combined with pyrohydrolysis for the separation of¹⁸F has been reported. The irradiation energy was operated at 20 MeV to avoid the interference from Na, because Na is one of the major element in rocks and¹⁸F is also produced from Na via²³Na(,n)¹⁸F reaction above its threshold energy, 20.9 MeV. After irradiation, fluorine was extracted by pyrohydrolysis and separated as LaF₃ precipitate. It was ascertained that the average recovery of fluorine in standard rocks was about 90% and the precipitate was of high radiochemical purity. This method was applied to the analysis of ten GSJ rock reference samples and two USGS standard rocks issued by the Geological Survey of Japan and the United States Geological Survey, respectively. The detection limit of this method was 0.02 g/g, and the results obtained by this method were in good agreement with the recommended values. This method was easily applied to the determination of a few ppm level of fluorine in rock samples, such as ultrabasic rock and feldspar.     

Determination of yttrium in rare earths by photon activation analysis

The determination of yttrium in the presence of large amounts of the rare earths by the thermal neutron reaction (89)Y(n, gamma)(90)Y is complicated because of frequent problems of sample self-shielding from major constituents of the sample, and the difficulty of separating (90)Y, a pure beta-emitter, from other elements which are very similar chemically. A non-destructive photon activation analysis method has been developed for this determination. Bremsstrahlung from a 35-muA beam of 35-MeV electrons induces the photonuclear reaction (89)Y(gamma, n)(88)Y. Optimum sensitivity is obtained by coincidence counting of the 0.90 and 1.84 MeV gamma-rays associated with the decay of (88)Y. The detection limit is less than 1 mug of yttrium.