Multi-element analysis of soils by computerized instrumental neutron activation analysis

The applicability of instrumental neutron activation analysis (INAA) for soils is described and demonstrated and its restrictions mentioned.     

Multi-element determination in silicate rocks by instrumental neutron activation analysis

Instrumental neutron activation analysis technique was applied for the determination of 20 elements in 54 silicate rock samples which belong to three sedimentary geological formations located in the western desert of Iraq. The samples along with USGS standards were irradiated in an IRT-5000 reactor at a neutron flux of 3.7·10¹³ n·cm^–2·s^–1 The following minor and trace element constituents have been determined: Na, K, Ca, Fe, Sc, Cr, Co, Zr, Ce, La, Nd, Sm, Eu, Tb, Yb, Lu, Hf, Ta, Th and U.     

Multi-element determination in sandstone rock by instrumental neutron activation analysis

Summary Instrumental neutron activation analysis (INAA) was used for the qualitative and quantitative analysis of sandstone samples of Aswan area, in South Egypt. The samples were properly prepared together with standards and simultaneously irradiated by a neutron flux of 7 ^. 10¹¹ n ^. cm^-2.s^-1. in the TRIGA research reactor facilities in Mainz. The gamma-spectra from a hyperpure germanium HPGe detector were analyzed. The present study provides the basic data of elemental concentrations of a sandstone rock. The following elements have been determined: Na, K, Fe, Sc, Cr, Co, Zr, Ce, La, Nd, Sm, Eu, Yb, Lu, Hf, Ta, Th and U. Energy dispersive X-ray fluorescence (EDXRF) was used for comparison and to detect elements which can be detected only by this method.     

Determination and geochemical significance of trace elements in Iraqi crude oils using instrumental neutron activation analysis

The trace-element composition of crude oil was studied using instrumental neutron activation techniques and a large-volume high-resolution Ge(Li) detector. A total of 29 elements were determined in oils representing the various producing formations of the Iraqi oil fields. These were: Al, Ar, As, Au, Br, Ca, Cl, Co, Cr, Cu, Eu, Fe, Ga, Hg, K, La, Mn, Mo, Na, Ni, Re, S, Sb, Sc, Se, Sm, V, W and Zn. The significance of these trace elements in the geochemical investigation of crude oil is discussed.     

Multielemental analysis of soils by instrumental neutron activation analysis

The results of an instrumental neutron activation analysis of some elemental concentrations in different soil samples near the industrial areas at Tirupati, India, are reported. Altogether 14 elements, Sm, La, Cr, Co, Zn, Cs, Ce, Th, Rb, Na, K, Sr, Fe and Eu were determined. The samples were irradiated with neutrons at the 100 kW Triga - Mainz research reactor and the induced activities were measured by gamma-ray spectrometry using an efficiency calibrated high resolution high purity germanium (HPGe) detector in connection with a multichannel analyzer. The results are discussed.     

Multielement analysis of lichen by instrumental neutron activation analysis

Lichen (species Trypethelium Eluteriae) is analysed for different elements. Nondestructive instrumental neutron activation analysis is employed for the multielemental analysis. Gamma-ray spectrometry is used for the identification and quantitative estimation of elements. Concentrations of 24 elements are reported. Gamma-ray spectrum of the lichen irradiated for 16 hours, delayed for 10 days, and counted for 10 hours on a 50 cm³ coaxial Ge(Li) detector is given.     

Elemental analysis of limestone by instrumental neutron activation analysis

Limestone samples from Assuit Governrate in Upper Egypt were subjected to elemental analysis by instrumental neutron activation analysis and X-ray fluorescence techniques. The samples were properly prepared together with their standards and simultaneously irradiated in a neutron flux of the order 7 × 1011 n/cm² s using TRIGA research reactor at Mainz. After activation the samples were subjected to γ-ray spectrometry using a high purity germanium detection system and computerized multichannel analyzer. Nineteen elements: Na, Ca, Mn, Fe, Sc, Cr, Co, Zn, Sn, La, Ce, Nd, Eu, Sm, Yb, Lu, Hf, Th and U were analyzed. X-ray fluorescence spectrometry have been also used. The presence of any elements in higher or lower levels in certain limestone samples is contingent on the occurrence of its bearing minerals, nature of parent sediments and depositional environments of these sediments. The major elements in the samples were also observed to be among the elements that had high enrichment factors in the study of suspended dust particulate within and around cement industries. This confirms cement as the major contributor to the airborne particulate matter in the environs.     

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.     

Multi-element analysis of blood for trace metals by neutron activation analysis

Fourteen elements can be rapidly determined in whole blood by the neutron activation analysis procedure described. Three of these (Ag, Cl, Se) are measured after a 10-s irradiation and eleven others (Al, Ba, Br, Ca, Cu, I, Mg, Mn, Mo, Rb, V) are determined by a 180-s irradiation of a 1-cm³ sample of whole blood after destruction of organic matter and removal of sodium by hydrated antimony pentoxide. A further 13 elements (As, Au, Co, Cr, Cs, Fe, Hg, K, Na, Ni, Sb, Sc, Zn) are determined after overnight irradiation in the SLOWPOKE reactor.     

Multi-element characterization of high-purity titanium dioxide by neutron activation analysis

A radiochemical neutron activation analysis method for the determination of 34 elements in titanium dioxide has been developed. For the assay of indicator radionuclides with short and with long half-lives, the radiochemical separation was performed by anion exchange on a Dowex 1 × 8 column and by combination of cation and anion exchange on a Dowex 50W × 8 and a Dowex 1 × 8 column from HF- and HF/NH₄F-medium, respectively. With both separation modes, a selective removal of the matrix-produced radionuclides ⁴⁶Sc, ⁴⁷Sc and ⁴⁸Sc was achieved. A selective extraction of copper with dithizone from 15 mol/L HF enabled counting the intensive but unspecific 511-keV rays of ⁶⁴Cu for the determination of Cu. The limits of detection achieved were between 0.004 ng/g for Sm and 0.8 μg/g for Sn (via ¹²⁵Sb). The elements La, Mn and Th were determined by instrumental neutron activation analysis only. These techniques were applied to the analysis of two titanium dioxide samples of different purity grade. The results and limits of detection are compared with those of other methods.     

Multielement analysis of food spices by instrumental neutron activation analysis

Twenty-four elements in six food spices were estimated by non-destructive instrumental neutron activation analysis. The problems in determining Cu were discussed.     

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%.     

Erros in instrumental neutron activation analysis

Equations are derived for the statistical and systematic error in INAA. It is possible to use them for the definition of limits of decision, detection and determination.     

Errors in instrumental neutron activation analysis

Equations are derived for the statistical and systematic error in INAA based on single photopeaks. They may serve to predict the applicability of the method or to judge data obtained under well-known conditions.     

Chemical characterization of graphite by instrumental neutron activation analysis

Nuclear and commercial grade graphite samples were analysed by instrumental neutron activation analysis (INAA) using high flux reactor neutrons. Eleven elements (Na, K, As, Sc, Fe, Cr, Co, Zn, La, Ce, and Sm) were determined in eight samples of graphite (two nuclear grade and six commercial grade) by irradiating at a neutron flux of 3?×?10¹³ cm^?2 s^?1 in CIRUS reactor and assaying the activity by high-resolution gamma ray spectrometry using 40% relative efficiency HPGe detector coupled to an MCA. Concentrations of elements were determined by relative method of INAA. Results of both types of graphites as well as detection limits achieved by INAA method are discussed in the paper.     

Multielement determination in water by instrumental neutron activation analysis

Instrumental neutron activation analysis /INAA/ technique has been applied to a water sample to determine the elemental concentrations. The sample was irradiated with a neutron flux of 1.2×10¹² n cm^–2 s^–1 for two different periods followed by counting at three different decay times, using two coaxial type high-resolution Ge/Li/ detectors. The dominant elements determined in the water sample are Ca, Cl, Na, Mg, and K present in ppm-level while Co, I, Mn, Sm, and Sb are present in smaller amounts, approximately on the average 0.01 ppm. Only traces of other elements such as the rare-earth elements, Ag, As, Ba, Cu, Cd, Fe, Sr, W, Zn, seem to be present in the water sample.     

Multielement analysis by sequential instrumental and radiochemical neutron activation

We measured 37 elements in six USGS geological camples and one NBS biological orchard leaf (OL) sample, using sequential INAA and radiochemical group separation coupled with high resolution, high efficiency Ge(Li), and a Ge(Li) with anticoincidence shields. The elemental concentrations in these samples vary over three orders of magnitude. Our results agree very well with the reported values. The rare earth values in PCC-1 are 2–4 times lower than the reported values. Precise REE patterns are defined in USGS samples, which are characteristic of the total rock types. The REE pattern in OL is identical to the mineral apatite. In addition to the possibility that OL may be contaminated by local soil, it is also possible that the uptake of REE trace elements by plants from soil is perhaps dominated by accessory mineral such as apatite, or plants take up the REE from bulk soil in a preferential manner as a smooth function of the REE ionic radii.     

Industrial applications of instrumental neutron activation analysis

Neutron activation analysis is shown as a useful diagnostic technique in semiconductor industry. A better acceptance of the method for applications in industry has been achieved through a specialized analytical service. Its main application is the characterization of high purity silicon in all stages of production. Irradiation of large sample volumes allowes a very sensitive detection of impurities in silicon with detection limits down to 10^–16 g/g. Other applications discussed are the analysis of silicon carbide, quartz, pure water and titanium. Special techniques described are autoradiography, depth profiling and surface analysis. In semiconductor process technology NAA was used to monitor contamination of silicon wafers.     

Rare-earth elemental analysis of banded iron-formations by instrumental neutron activation analysis

Representative banded iron-formations (BIFs) from various locations of the eastern Indian geological belt were investigated by instrumental neutron activation analysis (INAA). After pre-concentration, irradiation was carried out using a neutron flux of 5.1·10¹⁶ m⁻²·s⁻¹, 1.0·10¹⁵ m⁻²·s⁻¹ and 3.7·10¹⁵ m⁻²s⁻¹, with thermal, epi-thermal and fast neutrons, respectively. The activities in these samples were measured by a HPGe detector. Ten rare-earth elements, such as La, Ce, Nd, Sm, Eu, Tb, Ho, Tm, Yb and Lu, have been qualitatively identified and quantitatively estimated in these samples. The present investigation is an example of employing a pre-concentration method for high iron-containing ores prior to neutron activation analysis.