Instrumental photon activation analysis of coal fly ashes using the internal standard method coupled with the standard addition method

Multielement determinations of coal fly ashes (NIST SRM-1633a and BCR CRM-38) have been carried out by instrumental photon activation analysis using 30 MeV bremsstrahlung and the internal standard method coupled with the standard addition method. In these determinations, some major and minor constituent elements in the samples were properly used as effective internal standards. As a result, it was demonstrated that concentrations of 18 elements were determined accurately and precisely. Furthermore, a similar multielement determination has also been examined using 20 MeV bremsstrahlung. In this case, it was proved that better results can be achieved, because all interfering reactions were eliminated completely.     

Internal standard activation analysis of silicon in steel

Non-destructive 14-MeV neutron activation analysis for silicon in steel has been applied with ⁵⁶Mn as internal standard.⁵⁶Mn is formed from the iron matrix via the ⁵⁶Fe(n,p)⁵⁶Mn reaction. Several methods of internal standardisation via⁵⁶Mn are discussed. The 0.84-MeV photopeak of ⁵⁶Mn is recommended if steel samples of about the same composition are to be analysed. Chemically analysed steel samples are used as silicon standards. A precision of 0.7% was obtained for an analysis plus standardisation time of 13 min. Special attention was paid to interferences produced by concentration changes of impurity elements. Several possible sources of errors were investigated.     

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.     

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.     

Determination of metal traces in tantalum by proton activation analysis

Procedures for determining traces of calcium, titanium, vanadium, chromium, iron, copper, niobium, molybdenum and tungsten in tantalum are described utilizing 11 MeV proton activation. The instrumental method of analysis with the use of a Ge(Li) detector and the radiochemical separation of the corresponding fractions are described. The formula for the calculation of the concentration of traces with the use of thick target yields is given. Experimental data on the thick target yields of radioisotopes⁴⁴Sc,⁵²Mn,⁵⁶Co,⁶⁵Zn,^93mMo,⁹⁶Tc are presented. Based on the experimental data, the detection limits are estimated at 1–10 ppb for the above mentioned metal traces in tantalum. The successful solution of the task of the simultaneous determination of nine elements in tantalum confirms the wide applicability of proton activation analysis.     

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.     

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).     

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.     

A new internal standard method for activation analysis and its application. Determination of Co,Ni, Rb,Sr in pepperbush by means of photon activation

A new internal standard method for activation analysis has been developed. This method is characterized by that a suitable element present originally in the sample is used as an internal standard and the comparative standard is prepared by applying the standard addition method to the duplicated sample. When a sample under examination contains W_ag of trace element A to be determined together with a known amount of element B which is usable as an internal standard, and when the comparative standard is prepared by adding W _a ^* g of accurately known small amount of the element A to the duplicated sample, even if the sample and comparative standard are irradiated separately by particles with different fluxes, W_a can be determined, easily by using the following equation: W_a=W _a ^* /[(A _R ^* /A_R)-1] Where A_R and A _R ^* are counting ratios of gamma-rays emitted by two radioactive nuclides produced from the element A and B in the sample and comparative standard, respectively. Neither correction of the inhomogeneities of flux between the sample and comparative standard, nor that of, the self-shielding effects are necessary for the present method. The usefulness of the method was examined through the determination of Co, Ni, Rb and Sr in pepperbush by means of photon activation, and the precision and accuracy of the method were proved to be valid.     

Determination of silicon in cast iron by 14 MeV neutron activation

Silicon in cast iron was analyzed by 14 MeV neutron activation—high-resolution γ-ray spectrometry. Silicon was detected as²⁸Al, the product of the²⁸Si(n, p)²⁸Al reaction. Interference of⁵⁶Mn was separated using a Ge(Li) detector and a biased amplifying system. The 1. 81 MeV gamma-radiation of⁵⁶Mn, which is the product of the⁵⁶Fe(n, p)⁵⁶Mn reaction of the matrix of cast iron, was used as an internal standard and for correction of the self-absorption of the 1. 78 MeV gamma-radiation of²⁸Al by the sample. The interferences of aluminum, phosphorus and manganese could be neglected according to the results calculated from their nuclear properties and contents in the cast iron of this experiment. The results of this method agreed well with the results of the usual chemical method, with errors less than 5% of the results, and the precision of the method was satisfactory with a C. V. of less than almost 6% for rapid analysis of silicon in cast iron. The analytical line through the origin with a slope of the mean value of the repetition experiments could be used as the analytical line with almost the same precision and accuracy of the results as for the analytical line calculated by the least squares method.     

Intercomparison and determination of environmental standard samples by instrumental neutron activation analysis

To identify and improve the analytical technique for air pollution research, four kinds of environmental standard samples, i.e., airbome particulate matter, coal flyash, soil and pine needle supplied from the NIST and the IAEA were analyzed using thermal and epithermal neutron activation techniques. Sample irradiation was done at the irradiation facilities (neutron flux, 1 · 10¹³ n·cm^–2·s^–1) of the TRIGA MARK-III Research Reactor in the Korea Atomic Energy Research Institute. The accuracy and precision for the analysis of 40 trace and toxic elements in the samples were compared with the certified and reported values, respectively. In the analytical results of all standard reference materials, the relative standard deviation were within the 15% except for 11 elements and the relative error were agreed within the 10–20% except for 13 elements. The benefit of epithermal activation was investigated and the optimum analytical condition is reported.     

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).     

Rapid determination of molar ratios in binary systems by 14 MeV neutron activation analysis

The magnetic characteristics of barium ferrite, a compound widely used for magnetic materials, depend on the molar ratio of iron(III) oxide to barium oxide. On account of this fact, activation analysis using 14 MeV neutrons was applied for the rapid and non-destructive determination of the molar ratio of iron(III) oxide to barium oxide in barium ferrite. Iron was detected as⁵⁶Mn produced from the⁵⁶Fe(n, p)⁵⁶Mn reaction, and barium as^137mBa originating from the¹³⁸Ba(n, 2n)^137mBa reaction. A linear relation was obtained between the ratio of counts of⁵⁶Mn and^137mBa and the molar ratio of iron(III) oxide to barium oxide; the corrected gradient of the experimental calibration curve, obtained with^137mBa internal standard, agreed well with the calculated value. The molar ratios of iron(III) oxide to barium oxide obtained by activation analysis and by chemical analysis were in good agreement.     

An internal standard method for the determination of tin and tungstein in cassiterite by photon activation analysis

A method is described for the simultaneous determination of tin and tungsten in cassiterite ores by photon activation analysis using both elements and zirconium and zinc as internal standards. By using a 15-MeV photon beam, some interfering reactions with higher threshold energies can be eliminated. Thus the data processing becomes simpler and more accurate. The proposed procedure can be used for the routine analysis of tin and tungsten in cassiterite samples.     

Comparison of nondestructive proton and neutron activation: The case of biological samples

The capabilities of reactor neutron and 12 MeV proton activation were evaluted on samples of orchard leaves, beef liver and bovine liver. Based on γ-ray spectrometry, As, Ca, Cu, Fe, Mo, Pb, Sr, Ti, Zn and Zr at levels ranging from 2 to 20 900 ppm were detected following proton activation of 1 hour. Al, Br, Ca, Cl, Cu, Mg, Mn, Rb and V (ranging from 0.4 to 20 900 ppm) were measured by neutron activation (1 min irradiation). As, Ba, Br, Cr, Co, Fe, Hg, La, Na, Rb, Sb and Zn (ranging from 0.2 to 2400 ppm) were determined following a 14 h neutron irradiation. Although covering different elements, the two techniques are comparable in their scope, i. e. detection limits that can be achieved and number of elements that can be detected simultaneously.     

Rapid determination of molar ratios in binary systems by 14 mev neutron activation analysis

The 14 MeV neutron activation analysis method was applied for the rapid and non-destructive determination of the molar ratios of iron(III) oxide and zinc oxide in zinc ferrites. Iron was detected as⁵⁶Mn produced from⁵⁶Fe by the (n, p) reaction, and zinc as the sum of the coincidence counts of the annihilation radiations of the positrons emitted from⁶³Zn and⁶⁴Cu produced from⁶⁴Zn by the (n, 2n) and (n, p) reactions respectively. The ratios of the counts of⁵⁶Mn and the sum of the coincidence counts were not linearly related to the molar ratios of iron(III) oxide and zinc oxide in zinc ferrites. However, by corrections of the mutual contributions to the counts, linear relations were obtained between the ratios of the counts and the molar ratios when the corrected sum of the coincidence counts was used as an internal standard. The experimental and theoretical slopes of the analytical lines agreed within a difference of approximately 10%. The deviations between the results of the activation analysis and those of the chemical analysis were less than 5% of the chemical results.     

Particle-induced X-ray emission analysis of Eastern Indian ferromanganese oxide ores

Summary Ferromanganese oxide ore samples were studied from four different mines by particle-induced X-ray emission (PIXE) technique using 3 MeV proton beam obtained from a 3 MV pelletron accelerator at the Institute of Physics, Bhubaneswar, India. After irradiation, the spectral data were analyzed by a GUPIX-2000 software. Large number of major, minor and trace elements have been estimated in these samples. It has been observed that there is a positive correlation among manganese and some elements like Ca, Co, Pb, Zn and Se, whereas V and Mo correlates with iron well.     

Charged particle activation analysis of phosphorus in biological materials

Charged particle activation analysis of phosphorus in biological materials using the³¹P (α,n)^34mCl reaction has been studied. Since^34mCl is also produced by the³²S (α,pn) and the³⁵Cl (α, α′ n) reactions, the thick-target yield curves on phosphorus, sulfur and chlorine were determined in order to choose the optimum irradiation conditions. As a result, it was found that the activation analysis for phosphorus without interferences from surfur and chlorine is possible by bombarding with less than 17 MeV alphas. The applicability of this method to biological samples was then examined by irradiating several standard reference materals. It was confirmed that phosphorus can readily be determined at the detection limit of 1 μg free from interferences due to the matrix elements.     

Epithermal neutron activation analysis using the monostandard method

A method is described for epithermal neutron activation analysis of 17 elements in granite rock samples using a single standard. Gold has been used as a single comparator due to its relatively high resonance integral value (I₀=400 barn). In addition, it is preferable to Co in order to obtain a large epithermal activation in a short irradiation. The method of calculation is simple and rapid and can be done using a small calculator. Epithermal activation is able to overcome the difficulty arising from changing irradiation position as well as increasing the number of determinable elements by eliminating the interference from undesired isotopes which have relatively high thermal cross section values (₀), when reactor neutron flux is used. The coupling of epithermal activation with the monostandard method has the advantage of using a small Cd-cover which overcomes most of the difficulties arising in the relative method with large volume cadmium filters.