Photon and proton activation analysis of iron and steel standards using the internal standard method coupled with the standard addition method

The internal standard method coupled with the standard addition method has been applied to photon activation analysis and proton activation analysis of minor elements and trace impurities in various types of iron and steel samples issued by the Iron and Steel Institute of Japan (ISIJ). Samples and standard addition samples were once dissolved to mix homogeneously, an internal standard and elements to be determined and solidified as a silica-gel to make a similar matrix composition and geometry. Cerium and yttrium were used as an internal standard in photon and proton activation, respectively. In photon activation, 20 MeV electron beam was used for bremsstrahlung irradiation to reduce matrix activity and nuclear interference reactions, and the results were compared with those of 30 MeV irradiation. In proton activation, iron was removed by the MIBK extraction method after dissolving samples to reduce the radioactivity of⁵⁶Co from iron via⁵⁶Fe(p,n)⁵⁶Co reaction. The results of proton and photon activation analysis were in good agreement with the standard values of ISIJ.     

Instrumental photon activation analysis of environmental materials using the internal standard method

In order to study effective applications of the photon activation analysis using the internal standard method, determinations of Cr, Co, Ni, Zn, As, Rb, Sr, Y, Zr, Nb, Sb, Cs, Ba, Ce and Pb in two marine sediments as environmental materials have been examined by the use of a personal computer-based gamma-ray spectrometer equipped with a micro-robot for sample changing. In these determinations, some major and minor constituent elements in the samples were properly used as effective internal standards to check the roles with each other. As a result, it was demonstrated that accurate and precise determinations of the above 15 elements were achieved efficiently and favourably.     

Highly accurate and precise multielement determination of environmental samples by means of photon activation using the internal standard method

In order to examine effective applications of the newly developed internal standard method, determinations of Cr, Co, Ni, Zn, As, Rb, Sr, Y, Zr, Nb, Cs, Ce and Pb in three environmental materials, such as pond, lake and estuarine sediments, have been tried by means of photon activation. In these examinations, some major constituent elements in the above sediments were properly used as excellent and effective internal standards. In consequence, it was confirmed that highly accurate and precise determinations of the above 13 elements were achieved easily and favourably.     

Instrumental photon activation analysis of soil samples using the internal standard method coupled with the standard addition method

Multielement determinations in the certified reference materials of soils (IAEA soil-5 and 7) have been studied fundamentally by instrumental photon activation analysis using the internal standard method coupled with the standard addition method. For the soil-5 sample, in the first place, the qualities of the comparative standards prepared by two processing methods were compared with each other. As a result, it was demonstrated that a highly accurate and precise multielement determination can be achieved easily by minor improvement in the processing method of the comparative standard to ensure homogeneity. The utility of this processing method for soil samples was proved further through a similar analysis in another soil sample (IAEA soil-7).     

Instrumental charged-particle activation analysis of several selected elements in biological materials using the internal standard method

In order to study instrumental charged-particle activation analysis using the internal standard method, simultaneous determination of several selected elements, such as Ca, Ti, V, Fe, Zn, As, Sr, Zr and Mo, in oyster tissue, brewer's yeast and mussel has been examined by using the respective (p, n) reactions and a personal computer-based gamma-ray spectrometer equipped with a micro-robot for sample changing. In the above determination, constant amounts of Y and La were added to the sample and comparative standard as exotic internal standards. As a result, it was demonstrated that concentrations of the above elements can be determined accurately and precisely.     

Simultaneous determination of Ti,Cr, Fe,Cu, Ga and Zr in aluminium alloys by charged-particle activation analysis using the internal standard method

In order to study the application of the new developed internal standard method to charged-particle activation analysis, simultaneous determination of Ti, Cr, Fe, Cu, Ga and Zr in several commercial aluminium alloys has been tried using the respective proton-induced reactions. As a result, it could be proved that the best precision and accuracy are also obtained in these determinations.     

Application of the internal standard method coupled with the standard addition method in photon activation analysis to trace characterization of environmental materials

The internal standard method coupled with the standard addition method has been applied to the analysis of environmental materials, such as urban particulate matter, vehicle exhaust particulates and coal fly ash by photon activation. High-resolution gamma-ray spectrometry makes possible to use multi-internal standard gamma-rays, in order to crosscheck the analytical results obtained from each internal standard. It was ascertained that this method can provide not only accurate analytical results but also the information of homogeneity of samples, correlation of elements in the sample, loss or contamination in the preparation process.     

An internal standard method for the determination of trace elements in cigarette tobacco by neutron activation analysis

An internal standard method has been applied for the determination of lanthanum, antimony, scandium, chromium, iron and cobalt in commercial cigarettes by neutron activation analysis using gold as an internal standard element. These trace elements were separated from irradiated samples by APDC (ammonium pyrrolidine dithiocarbamate)/Zeph (tetradecyl dimethyl benzyl ammonium chloride) coprecipitation, followed by direct gamma-counting of the separated precipitate using a Ge(Li) detector. Standard reference tobacco 1R1 prepared by the University of Kentucky was also analyzed by this procedure for the above 6 elements, the results of which were compared with literature values. Good results were obtained by the present method.     

The yields of photonuclear reactions for multielement photon-activation analysis

A comprehensive study on the yields of photonuclear reactions of various types has been performed, and sensitivities and the effects of interferences in multielement photon-activation analysis have been evaluated by bremsstrahlung activation of many elements with maximum energies ranging from 30 to 60 MeV. The applicability and reliability of the method were demonstrated by analyzing standard round-robin samples and then by presenting the elemental abundances in several geological, biological and environmental materials. The method was almost insensitive to matrix effects and was assessed to be promising for nondestructive multielement determination of the materials of wide variety, giving good reproducible results for 20 or more elements.     

Revaluation of the internal standard method coupled with the standard addition method applied to soil samples by means of photon activation

In order to achieve the highly accurate and precise multielement determination in environmental materials, the usefulness of the comparative standard provided by the processing method proposed previously for soil samples has been re-examined using calcareous loam soil, light sandy soil and river sediment as unknown samples. As a result, it was also demonstrated that concentrations of 15 trace elements in each sample can be determined effectively and reasonably.     

Contributions to accuracy improvement of simultaneous ICP atomic emission spectrometry using multi-line measurements of analyte and internal standard elements Applications for the analysis of permalloy

For successful application of simultaneous ICP atomic emission spectrometry for major component determinations in multi-component materials the accuracy of the method has to be improved. As a contribution to solve this problem a combined procedure for multi-component standard sample preparation, optimum calibration and different variations of internal standard corrections is described. Variance-weighted multi-line calibrations give most accurate results. Internal standard corrections are effective, if the time-dependent spectral line intensity fluctuations of the standard and the analyte elements are well correlated. Their sensitivities against some responsible device parameter variations are investigated. On the basis of multi-line measurements of the analyte and internal standard elements a “group-selected internal standard correction” (GS-ISC) method is applied and results in relative errors of less than 1% even for extreme fluctuations of the raw intensities. For rapid routine determination methods of materials with variable element compositions the added line intensities of the internal standard element can be used to correct the added analyte line raw intensities (“intensity addition internal standard correction” (IA-ISC) method). These accuracy optimization procedures are applied for the analysis of the soft magnetic material permalloy using the internal standard element In.     

Multielement determination in tobacco leaves by photon activation analysis

A nondestructive photon activation procedure with 30 MeV bremsstrahlung followed by high-resolution gamma-spectrometry has been applied to the multielement determination in tobacco leaves and commercial cigarettes. The elements determined by this method included essential minor elements such as Ca, Cl, K and Mg, essential trace elements such as Fe, Mn and Zn, and possibly toxic elements such As and Sb. The NBS Orchard Leaves could successfully be used as a comparative standard. The method is quite simple and gives good reproducible results for at least 12 elements.     

Multielemental photon activation analysis of copper-molybdenum ores and products of processing using a microtron bremsstrahlung

A method of Multielemental Instrumental Photon Activation Analysis (IPAA) of copper-molybdenum ores and its products processing using microtron bremsstrahlung is described. The activities of the irradiated samples were measured by means of Ge(Li) and HP-Ge-detectors. Quantitative determinations of elements were performed on standard reference materials. This method allows the determination of 10–24 elements in the samples. The results of these IPAA measurements are compared with the data of the Mongolian reference materials of copper-molybdenum ores and the products of processing.     

Non-destructive determination of chlorine in organic compounds by neutron-capture gamma-ray measurement,using an isotopic neutron source

Neutron-capture γ-ray activation analysis was investigated using a 300 mCi Am?Be neutron source. Prominent photopeaks available for the analysis were observed in several high-sensitivity elements, e.g. 0.477 MeV for boron, 0.336 MeV for samarium, 0.559 for cadmium, 0.230 MeV for cobalt, 0.370 MeV for mercury, and 0.518 MeV and 0.792 MeV for chlorine. As a practical application of the method, determinations of the chlorine contents of various organic compounds were carried out, and it is shown that Cl contents of 5–50 w/v% can be determined in this way with an experimental error of less than 5%.     

Quantification of residual monomer in polylactide by gas chromatographic internal standard method

An analytical method has been developed to quantitatively determine the residual lactide monomer in polylactide (PLA) using an internal standard method of gas chromatography (GC). The experimental results showed that diphenyl ether (DPE) was an appropriate internal standard for quantitative analysis of residual lactide in PLA. PLA and DPE were dissolved in dichloromethane and precipitated in hexane. At the same time, the residual lactide in PLA and DPE as an internal standard were extracted to hexane from the polymer solution. The resulting solution could be directly injected into a GC system. Therefore, the residual lactide was determined quantitatively using an internal standard method of GC. This method is practical for measuring the residual lactide content in PLA. When the lactide content is 5.0%, the relative standard deviation (RSD) of the measurements is 1.7%, while RSD is 6.9% at the low level of 0.4%, which indicates that the method is sufficiently precise.     

The influence of sample properties and sample geometry on the accuracy of gamma-ray spectrometric analyses

Nuclear isomers of half-lives above one second have been excited from the ground state of stable nuclides via inelastic γ-ray scattering by using bremsstrahlung of a 4 MeV, 22 μA linear electron accelerator. This method is potentially useful for a number of elements in elemental analysis by virtue of its high specificity and, in some cases good sensitivity. As there is no need for special sample preparation, this kind of activation may be preferable in some applications. Detection sensitivities have been determined for 15 elements, and possibilities in routine chemical analysis are 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%.     

X-ray diffractometric determination of sub-milligram amounts of hematite by a suspension-filtration method with silicon as internal standard

Silicon powders of four particle-size ranges were prepared from reagent-grade silicon by the Andreasen pipet method and elutriation. Thin-layer specimens were prepared by a suspension-filtration method using membrane filters. Silicon powder of 1.0–2.5 μm diameter is recommended as internal standard from the study of particle-size effects. Stable suspensions of silicon and hematite were prepared with a 0.05% dextrin solution. Relative standard deviation for determinations by the internal-standard method were < 9% for 100 μg of hematite in a mixed powder sample of 600 μg and < 5% for 400 μg of hematite in mixed samples of 900–1400 μg. Absorption effects in mixed powders are discussed.     

Application of the k0 standardization method in reactor nuetron activation analysis of standard steels and fly ash

The method of k₀ standardization is suitable for routine multi-element determinations by reactor neutron activation. Investigation of NBS steel standards showed the systematic error of the method to be less than 3%. Numerical evaluation of the spectra was found to be fast and convenient. Fourteen elements in the steel samples were determined; for nine, the standard deviation was less than 4%. Thirty seven elements were determined in NBS SRM-1663a Coal Fly Ash; agreement with certified values was again very good.     

Application of k0-based internal mono standard instrumental neutron activation analysis method method for composition analysis of stainless steel clad sample

The k₀-based internal mono standard instrumental neutron activation analysis (INAA) method was used for the composition analysis of some irregular shape stainless steel (SS) samples of type SS 316M, which is used as fuel cladding in Indian fast breeder test reactor (FBTR). The method utilizes in situ relative detection efficiency using γ-rays of the activation products present in the sample for overcoming γ-ray self-attenuation. Samples were neutron activated using the thermal column as well as the core position of the reactor and the assay of radioactivity was carried out by high-resolution gamma ray spectrometry. The elements determined were Fe, Cr, Ni, Mo, Mn, Co, Cu, As and W. Since all the major elements (Fe, Cr, Ni, Mo and Mn) were amenable to NAA, the relative elemental concentrations with respect to Fe, obtained by this method, were converted to their absolute values by mass balance. The results were compared with specified compositions and found to be satisfactory. In order to validate these results obtained by the standard-less approach, sub samples of SS 316M in solution forms were analyzed by prevalent relative and k₀ methods of INAA, and results were found to be in good agreement. The accuracy of the internal mono standard INAA method has been evaluated by analyzing an alloy steel certified reference material, CRM 225/1 of British Chemical Standards (BCS).