Multielement trace analysis of high purity aluminium by neutron activation

Instrumental neutron activation analysis was applied to multielement trace analysis of high purity aluminium samples. In order to reduce the production of²⁴Na from the matrix, samples were activated by thermal neutron flux of high cadmium ratio. Detection limits of various impurity elements were evaluated. So called “five nine” class standard aluminium samples were analyzed and concentrations of various impurity elements were determined. The analytical results obtained on zone refined aluminium samples showed that zone refining is effective against many elements, such as Na, Cr, Fe, Co, Cu, Ga, As, Br, Ba, La, Ce, Sm, Yb, Lu, Hf, W, Th and U, but not very effective against the element Sc.     

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.     

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.     

Multielement instrumental neutron activation analysis of silver-copper coins

Neutron activation, applied to silver and copper based coinage, leads to a measure of the mean concentrations of major and 12 trace elements, even if their distribution is heterogeneous. The drawbacks of this activation method applied to such a matrix are shielding effects and high radioactivity of major elements. Both effects were avoided by accurately calculating the correction coefficients and by choosing the optimal working conditions. Analytical results obtained lead to a better knowledge of the chronology and origin of Armorican protohistorical coinage.     

Multielement neutron activation analysis of an iron ore

Multielemental analysis of an iron ore from the Kingdom of Saudi Arabia was carried out using Instrumental Neutron Activation Analysis (INAA) with Ge(Li) detectors. The spectra were analysed with the help of an off-line computer programme. Twenty five elements are observed to be present in the ore. The elements of major interest are Fe, Al and Ca with 51.5%, 3.6% and 2.2% concentrations, respectively.     

Multielement standards in routine reactor neutron activation analysis

The application of multielement standards (MES) in routine neutron activation analysis brings a whole range of advantages. This paper deals with the experience obtained during many years of application of these MES. Nine of these MES contain a total of 50 elements in suitable combinations and concentrations; thus, the determination of most of the common elements by NAA can be carried out simultaneously. This refers to the following elements: Na, Mg, Al, Cl, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Br, Rb, Sr, Mo, Ag, Cd, In, Sb, Te, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, W, Re, Au, Hg, Th and U. For the determination of the remaining elements such as Zr, Ta, Ir etc., single element standards (SES) are used.     

Acid leaching purification and neutron activation analysis of high purity silicas

The effects of acids on the removal of impurity from 2N grade silica have been studied using five leaching acids: 0.2 M-oxalic acid (pH 1.5 and 2.5), c-aqua regia, 2.5%—HCl/HF, and 1%—HNO₃/HF. The presence of 39 impurities in the 2N grade silica and the reference material (RM, 5N grade silica) were investigated by neutron activation analysis (NAA), X-ray fluorescence (XRF), and inductively coupled plasma mass spectrometry (ICP-MS) methods. Major impurities of the 2N silica were Al, K, Fe, Na, Ti, Ca, Mg and P. The fractions of the eight major impurities were 99.2% and 90.9% of total impurity in the 2N and RM silica, respectively. Among the leaching acids, almost all of the major impurities were removed effectively by the 2.5% HCl/HF leaching acid. All the major impurities, except for phosphorous, as well as 21 minor and trace impurities could be determined by the NAA.     

Radiochemical neutron activation analysis of trace impurities in high purity aluminum

Rapid radiochemical neutron activation analysis (RNAA) procedures were developed and employed for the determination of 32 trace impurities in high purity aluminum thin foils. Anion exchange column chromatography was developed for the sequential group chemical separation of various elements which helped in reducing the spectral interferences and improving the sensitivity of the method. The procedure is simple and requires a very short time to separate the elements in three groups for radiometric assay. To determine very low contents of uranium and thorium,²³⁹Np and²³³Pa as activation products were separated using anion exchange and coprecipitation methods. The impurity contents were found to be low, therefore, their adverse effects on microelectronic devices would be negligible. Our data could partially be compared with the data reported in literature.     

Determination of cadmium using radiochemical neutron activation analysis

A method has been developed for the determination of cadmium in samples of food and biological materials using neutron activation analysis with radiochemical separation. The irradiated sample is digested in presence of cadmium carrier, with a nitric-perchloric mixture, evaporated to dryness, dissolved in 6M HCl and placed onto an ion exchange column loaded with Dowex 1-X8 resin in chloride form and conditioned with HCl 6M. The cadmium is retained in the resin. After a washing procedure with several portions of HCl of decreasing concentration, the cadmium is eluted with an ammonia-ammonium chloride buffer. The activity of ^115mIn which is in equilibrium with ¹¹⁵Cd, is measured using a NaI(Tl) well type detector. The method has been evaluated by analyzing certified reference materials with cadmium concentrations covering a range of 0.020 to 200 mg^.kg^-1. The agreement of the results with the certified values is within 95%, which gives an indication of the sensitivity and accuracy of the proposed method.     

Multielement content of coal by neutron activation analysis techniques

Due to the interaction with components present in natural waters, radionuclides may be present in different physico-chemical forms, varying in size, charge and density. The distribution pattern will influence the transport, mobility and biological uptake of the radionuclides. Size fractionation based on hollow fiber is useful for the determination of the size distribution pattern of radionuclides in natural waters. Furthermore, a continuous mixing and separation system has been developed for the investigation of the association of radionuclides with naturally occurring colloids. Results based on radionuclides in waste water from the Forsmark nuclear power plant, Sweden, will illustrate the potential usefulness of the technique.     

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.     

On processing standards in radiochemical neutron activation analysis

In radiochemical neutron activation analysis, standards may be measured directly or subjected to the same radiochemical processing as the sample. Some considerations in regard to processing are examined, and the advantages and disadvantages of this approach discussed. It is concluded that processing of standards is often inadvisable and can lead to errors, particularly if used as a substitute for radiochemical yield determinations.     

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 determination in river water by neutron activation analysis

Concentrations of Al, Br, Ca, Ce, Co, Cr, Eu, Fe, Hf, La, Lu, Mg, Mn, Na, Rb, Sc, Sm, Sr, Tb, Th, Ti, V, Yb, Zn, and Zr have been measured in Tigris and Euphrates river water, using neutron activation analysis in combination with preconcentration technique. River water samples were preconcentrated by evaporation at 70°C under atmospheric pressure. The samples with standard reference materials were irradiated with a neutron flux of 2.3·10¹³ n·cm^–2·s^–1.     

Substoichiometric determination of Hg by radiochemical neutron activation analysis

A rapid method has been developed for the determination of mercury in environmental samples by thermal neutron activation analysis. Radiochemical separation involves the extraction of Hg/II/ with substoichiometric amounts of 2-mercaptobenzothiazole /2-HMBT/ into chloroform¹. The time required for radiochemical purification and counting of two samples and a standard is about 2 h. Water, sludge and IAEA standard samples were analyzed for Hg concentration by this method.     

Multielement analysis of Nigerian chewing sticks by instrumental neutron activation analysis

In Nigeria, various parts of various species of native plants have long been used for dental hygiene, with reportedly considerable effectiveness. These materials are known as “chewing sticks”. This study was an effort to ascertain whether any unusual trace element concentrations might be present in Nigerian chewing sticks. Results are presented for 17 elements (Na, Mg, Al, Cl, K, Ca, Sc, V, Mn, Fe, Co, Zn, Br, Cs, La, Sm, Au) detected and measured in 12 species of such plants, via instrumental thermal-neutron activation analysis.     

Multielement analysis of Northwestern Nigerian rocks by instrumental neutron activation analysis

Rock samples from seven different locations in northwestern Nigeria were analyzed by reactor instrumental neutron activation analysis and Ge(Li) gamma-ray spectrometry. Concentration values were obtained for 18 elements (As, Ce, Co, Cr, Cs, Eu, Fe, Hf, La, Lu, Sc, Sm, Sr, Ta, Tb, Th, U, Yb). The geochemical implications of the results are discussed.     

Multielement standards for instrumental neutron activation analysis of biological materials

Standards for instrumental neutron activation analysis (INAA) of biological materials are proposed. The standards are multielement solid solutions in phenol-formaldehyde resole resin (PFR) moulded as pellets weighing 30 to 50 mg. The concentrations of trace elements in the standards are selected so that, firstly, they are commensurable with their concentrations in the biological materials and, secondly, that the analytical lines of each of the elements incorporated in PFR are resolved with the aid of modern equipment. The principal standard contains 21 trace elements from among those of greatest interest for INAA of biological materials. This standard is recommended for work on high-resolution equipment. At the same time, standards of simpler trace element composition have been prepared and studied which can be used in work on simpler equipment or in solving particular problems in determination of certain groups of chemical elements.     

Precise trace rare earth analysis by radiochemical neutron activation

A rare earth group separation scheme followed by normal Ge(Li), low energy photon detector (LEPD), and Ge(Li)−NaI(Tl) coincidence-noncoincidence spectrometry significantly enhances the detection sensitivity of individual rare earth elements (REE) at or below the ppb level. Based on the selected γ-ray energies, normal Ge(Li) counting is favored for¹⁴⁰La,¹⁷⁰Tb and¹⁶⁹Yb; LEPD is favored for low γ-ray energies of¹⁴⁷Nd,¹⁵³Sm,¹⁶⁶Ho and¹⁶⁹Yb; and noncoincidence counting is favored for¹⁴¹Ce,¹⁴³Ce,¹⁴²Pr,¹⁵³Sm,¹⁷¹Er and¹⁷⁵Yb. The detection of radionuclides^152mEu,¹⁵⁹Gd and¹⁷⁷Lu is equally sensitive by normal Ge(Li) and noncoincidence counting;¹⁵²Eu is equally sensitive by LEPD and normal Ge(Li); and¹⁵³Gd and¹⁷⁰Tm is equally favored by all the counting modes. Overall, noncoincidence counting is favored for most of the REE. Precise measurements of the REE were made in geological and biological standards. Prepared for the U.S. Department of Energy under Contract DE-AC06-76RLO 1830.     

Multielement determination in soil extracts by instrumental neutron activation analysis

Forest Swiss soils from 39 locations sampled ad three depths each were extracted with a buffered solution of pH 4.65 containing EDTA. Nearly 30 elements were determined by instrumental neutron activation analysis in these extracts. The results obtained are discussed in terms of efficiency of the extractant, precision and accuracy. Summariszed results are presented for the quantities fractions of the elements extracted.