TDCR measurements of 3H, 63Ni and 55Fe using Hidex 300SL LSC device

The commercial Hidex LSC system has been used to measure triple to double coincidence ratio (TDCR), experimental counting efficiency (CE) and the absolute activity for radioactive standards of pure beta emitters viz. ³H, ⁶³Ni and ⁵⁵Fe, an electron capture nuclide. Colour and chemical quench measurements of ⁶³Ni and ⁵⁵Fe have been done. An excellent match between TDCR and CE has been obtained for beta emitters, while very large deviations have been observed for ⁵⁵Fe. The deviation between TDCR and experimental efficiency has been found to be nearly uniform. Based on this, an empirical correction factor for TDCR which gives the correct efficiency has been evaluated, to enable efficient application of this commercial instrument for ⁵⁵Fe estimation. These TDCR correction factors were further validated by applying for ⁵⁵Fe activity measurements in ASTM standard steel samples irradiated to a fixed neutron flux in research reactor CIRUS. Finally, ⁵⁵Fe activity in steel sample from APSARA reactor decommissioning waste was successfully estimated using this modified TDCR.     

Determination of Si,Al, Ti,Fe and Zr in glass sand samples by 14 MeV neutron activation analysis

Fast neutron activation analysis technique was applied for the determination of Si, Al, Ti, Fe and Zr in glass sand rock samples. The samples and standards were irradiated with a mono-energetic neutron flux of 10⁸n · cm^– · s^–1. Pneumatic facility was used. The gamma activities from samples and standards were counted using a 30 cm³ Ge(Li) detector, with FWHM of 2.9 keV at 1.332 MeV, coupled to an on-line computer facility.     

Evaluation of a sensitive,reasonable, and fast detection method for 55Fe in steel

Journal of Radioanalytical and Nuclear Chemistry - A pilot study to quantify 55Fe in steel from a reactor vessel of a nuclear power plant by accelerator mass spectrometry (AMS) without any chemical...     

Determination of Si,Al, Fe,Mg in rock samples by the 14-MeV neutron activation method

The determination of Si, Al, Fe and Mg in rocks of Albanian origin by 14-MeV neutron activation technique is described.     

Determination of Fe and Zn in biological samples by radiochemical neutron activation analysis

Radiochemical NAA methods have been developed for the simultaneous determination of Fe and Zn in biological samples. The method involves reactor irradiation, dissolution in 3M HCl and solvent extraction followed by counting on a scintillation gamma-ray spectrometer. Iron was separated with aqueous cupferron and extracted into chloroform while Zn was extracted with 2-thenoyl trifluoroacetone (TTA) into methyl isobutyl ketone (MIBK). Reaction conditions such as pH and the effect of solvents and various ions were studied using tracer activities. The methods have been employed for trace level determination of Fe and Zn in NBS, SRMs, Bowen's Kale, IAEA CRMs and other plant leaves.     

电感耦合等离子体原子发射光谱法测定钨合金中镍、铁、钴和锰

采用电感耦合等离子体原子发射光谱法测定钨合金中镍、铁、钴和锰的含量。优化的试验条件如下:1柠檬酸溶液用量为2mL;2过氧化氢溶液用量为12mL;3称样量为0.100 0g;4氨水溶液用量为2mL。选择镍、铁、钴、锰的分析谱线分别为221.647,233.280,228.616,259.373nm。4种元素在一定的质量浓度范围内与其发射强度呈线性关系,方法的检出限(3s/k)在0.018~0.083mg·L-1之间。方法应用于标准物质(JBWY05901)的分析,测定值与认定值相符。方法用于生产样品和合成样品的分析,测定值的相对标准偏差(n=6)在0.72%~3.9%之间。     

Intercomparison exercise on difficult to measure radionuclides in activated steel: statistical analysis of radioanalytical results and activation calculations

Journal of Radioanalytical and Nuclear Chemistry - This paper reports the results obtained during an intercomparison exercise for the determination of difficult to measure radionuclides in...     

Determination of Al,Si and O in isolated steel inclusions by 14 MeV neutron activation analysis

The method of non-destructive analysis for Al, Si and O in non-metallic inclusions isolated from steel is presented. The small powdered samples varying in mass from 2 mg to 40 mg were analysed, thus making the development of a proper technique of sample preparation necessary. The specific activation geometry and rotation of samples during irradiation were chosen to improve the accuracy and precision. Lower limits of determination for Al, Si, and O were: 1.4 mg, 0.3 mg, and 0.8 mg, respectively.     

ICP-AES法测定AuNiGd合金中的Ni、Gd、Pd、Fe和Bi

报道了采用ICP-AES法测定AuNiGd合金中Ni、 Gd、 Pd、 Fe、 Bi.对测定元素的波长、测定条件进行了选择;考察了基体和无机酸对测定的影响;在优化条件下,对试样进行测定,其相对标准偏差(n＝15) Ni 1.6%、 Gd 1.8%、 Pd 13%、 Fe 4.9%、 Bi 13%;回收率 Ni 98%～105%、 Gd 97%～99%、 Pd 101%～105%、 Fe 98%～104%、 Bi 104%～106%.     

Stopping powers and inelastic mean free path from quantitative analysis of experimental REELS spectra for electrons in Ti,Fe, Ni,and Pd

Stopping power (SP) and inelastic mean free path (IMFP) of electrons in Ti, Fe, Ni, and Pd have been determined by using dielectric models. We have used energy loss function (ELF) determined from quantitative analysis of experimental reflection electron energy loss spectroscopy (REELS) spectra as the input parameter for this model. ELF in this study was determined from the previously published quantitative analysis of REELS spectra. The SP of Fe, Ni, Pd, and Ti was compared with several calculation methods for energies from 100 eV to 10 keV and shows SP in this study, which are in best agreement for medium to high energies (greater than or equal to 300 eV). The IMFP obtained in this study shows the best agreement with online database TPP2M and NIST and also calculation by Tanuma with a root mean square (rms ) less than 12%. The present approach shows ELF from quantitative analysis of REELS spectra has a high potential for the experimental determination of SP and IMFP of metals.     

Thermal analysis,microstructure and impurity phases evolution in Fe14Cr ferritic steel powders ball-milled in air and under an argon atmosphere

Journal of Thermal Analysis and Calorimetry - Azobenzenes undergo reversible trans–cis photo-isomerization and have been studied extensively as photo-responsive materials. Despite their...     

Determination of Cd, Co, Cr, Cu, Fe, Ni and Pb in Milk, Cheese and Chocolate

 Combined analytical procedures consisting of wet digestion step followed by instrumental determination – differential pulse cathodic stripping voltammetry (DPCSV) or electrothermal atomic absorption spectrometry (ETAAS) – as well as a direct analysis method – slurry sampling ETAAS – for the determination of Cd, Co, Cr, Cu, Fe, Ni and Pb in milk, cheese and chocolate are described and compared. Wet digestion using a mixture of HNO₃-HClO₄-H₂O₂ is proposed for complete matrix decomposition prior to trace analyte determinati on by DPCSV or ETAAS. A mixture of HNO₃-H₂O₂ is used for slurry preparation. Optimal instrumental parameters for trace analyte measurements are presented. The reliability of the procedures has been verified by analyzing standard reference materials. Results obtained are in good agreement with the certified values and the relative standard deviations (for these results) are in the range 5–10% for wet digestion DPCSV or ETAAS and 3–9% for slurry sampling ETAAS in the range of 2 μgċg⁻¹ (Cd) to 12 μgċg⁻¹ (Fe). Received August 24, 1999. Revision January 20, 2000.     

Simultaneous spectrophotometric determination of Fe and Ni with xylenol orange using principal component analysis and artificial neural networks in some industrial samples

Artificial neural networks (ANNs) are among the most popular techniques for nonlinear multivariate calibration in complicated mixtures using spectrophotometric data. In this study, Fe and Ni were simultaneously determined in aqueous medium with xylenol orange (XO) at pH 4.0. In this way, after reducing the number of spectral data using principal component analysis (PCA), an artificial neural network consisting of three layers of nodes was trained by applying a back-propagation learning rule. Sigmoid transfer functions were used in the hidden and output layers to facilitate nonlinear calibration. Adjustable experimental and network parameters were optimized, 30 calibration and 20 prediction samples were prepared over the concentration ranges of 0-400 mug l(-1) Fe and 0-300 mug l(-1) Ni. The resulting R.S.E. of prediction (S.E.P.) of 3.8 and 4.7% for Fe and Ni were obtained, respectively. The method has been applied to the spectrophotometric determination of Fe and Ni in synthetic samples, some Ni alloys, and some industrial waste waters.     

The use of14C,59Fe and65Ni radionuclides for the study of solvent effects on the extraction equilibria with n-caprylic acid

The distribution of n-caprylic acid between an aqueous sodium sulphate solution and several organic diluents of various properties has been investigated, using¹⁴C-labelled n-caprylic acid. The distribution coefficients of the monomeric capyrlic acid and its dimerization constants in the organic phase were determined. The extraction of Fe(III) and Ni(II) with n-caprylic acid solutions in various diluents was studied using the AKUFVE solvent extraction equipment. The composition of the extracted compound of Fe(III) has been determined and the extraction constants for all the studied systems have been calculated. For the extraction of Ni(II) the constants of the extraction of nickel caprylate monomers and its dimerization constants in the organic phase have been calculated.     

A comparison between cold and thermal neutron prompt gamma activation analysis in the determination of carbon,nitrogen, and phosphorus in cattail

Methods for the determination of total carbon (TC), total nitrogen (TN), and total phosphorus (TP) in cattail (Typha domingensis) using cold and thermal neutron prompt gamma activation analysis (CNPGAA and TNPGAA) have been developed in the CNPGAA and TNPGAA facilities at the National Institute of Standards and Technology (NIST), and evaluated through the analysis of Standard Reference Materials (SRMs) in previous studies. There are major issues that impact the sensitivities of C, N and P using CNPGAA and TNPGAA including the effects of hydrogen content in samples, sample thickness and Compton scattering. However, interference from chlorine (Cl) in cattails has a major impact on the detection of P. This paper compares the effects of hydrogen content, sample thickness and Compton scattering on the sensitivities of C, N, and P between CNPGAA and TNPGAA and provides a resolution to the Cl interference on P in cattail.     

Adsorption of organic probes on silica through Lewis interactions: a comparison of experimental results and quantum chemical calculations

The adsorption of organic probe molecules on a partly dehydroxylated silica (SiO(2)) surface has been studied in a non-aquatic and non-polar environment. These results were compared to, verified and explained by quantum chemical calculations on the same systems. Since the systems are water free and since the non-polar solvent cyclohexane is used in the experiments, the quantum chemical calculations are well comparable to the experimental results without any additional terms. The characterized surface was found to contain both Lewis acid and Lewis base sites and a good agreement between the experimentally determined and the calculated data was found.     

Monte Carlo calculations and neutron spectrometry in quantitative prompt gamma neutron activation analysis (PGNAA) of bulk samples using an isotopic neutron source

An activation analysis facility based on an isotopic neutron source (185 GBq ²⁴¹Am/Be) which can perform both prompt and cyclic activation analysis on bulk samples, has been used for more than 20 years in many applications including 'in vivo' activation analysis and the determination of the composition of bio-environmental samples, such as, landfill waste and coal. Although the comparator method is often employed, because of the variety in shape, size and elemental composition of these bulk samples, it is often difficult and time consuming to construct appropriate comparator samples for reference. One of the obvious problems is the distribution and energy of the neutron flux in these bulk and comparator samples. In recent years, we have attempted to adopt the absolute method based on a monostandard and to make calculations using a Monte Carlo code (MCNP4C2) to explore this further. In particular, a model of the irradiation facility has been made using the MCNP4C2 code in order to investigate the factors contributing to the quantitative determination of the elemental concentrations through prompt gamma neutron activation analysis (PGNAA) and most importantly, to estimate how the neutron energy spectrum and neutron dose vary with penetration depth into the sample. This simulation is compared against the scattered and transmitted neutron energy spectra that are experimentally and empirically determined using a portable neutron spectrometry system. This revised version was published online in August 2006 with corrections to the Cover Date.