Activation analysis of biological maternal with ruthenium as a multi-isotopic comparator

The elements Fe, Zn, Se, Rb and Co were determined in NBS bovine liver (SRM 1577) by non-destructive activation analysis; ruthenium was used as triple comparator element. The results were compared with the values of the analysis certificate and with those of an analysis based on a multi-element serum standard; the agreement was excellent. The conclusions of the error theory of the comparator method were experimentally confirmed.     

Neutron activation analysis for provenance studies of archaeological ceramics

Neutron activation analysis was used for provenance studies of ceramics from the early middle ages (avar period). 14 trace elements and Fe were determined by multiisotope comparator method. Computerized mathematical statistical methods (cluster-, and similarity analysis) were used for grouping the samples according to the similarity of their trace element distributions.To the memory of János BÉRCZI.     

CINA — A program for complete instrumental neutron activation analysis with a PC-type minicomputer

A program has been developed to use a PC-type minicomputer for instrumental neutron activation analysis. The program has the capacity for photopeak search, peak area computation, and element concentration determination using the single comparator method. Analysis time for a 4096-channel spectrum containing 20 photopeaks is about 4 minutes.     

Determination of rare-earth elements in steels by radiochemical neutron activation analysis

For the separation of rare-earth elements from steel, with a cation exchange resin, separation experiments were performed on NIST reference materials of SRM-363 and SRM-364. Iron, Na, Cr, Mn, Co, Cu, As, Mo, Sb and W were separated in 2M hydrochloric acid, five rare-earth elements, La, Ce, Pr, Nd and Sm and three other elements, Hf, Zr and Ba were separated using 8M nitric acid. Each element was determined by a single comparator method using two monitors, gold and cobalt.     

The internal comparator method

An internal comparator method is proposed which offers reliable instrumental neutron activation analysis (INAA) results for samples with an irregular geometry and/or measured at the closest position to the Ge detector. Because the selected internal comparator in the sample analyzed will receive exactly the same thermal neutron flux as the other components, this method can be applied to the INAA of materials suffering from thermal neutron self-shielding. To apply the internal comparator method, the k₀-method must be installed and the analytes, including the internal comparator, should be homogeneously distributed in the test portion.     

Multi-elemental epithermal neutron activation analysis using an internal single comparator

Epithermal neutron activation analysis using an internal single comparator has been used for the analysis of Saudi Arabian iron ores. The concentration of thorium, barium, terbium, tantalum, cobalt, lanthanum and antimony was determined using iron in the ore as an internal comparator for all the elements. In case of antimony there was an agreement between this method and the conventional method indicating that the given method is accurate.     

Fast neutron activation analysis of rare-earth elements in monazite from Korea

The relative ans single comparator methods have been applied to determine 7 rare-earth elements and U, Th in Korean Monazites by 14.5 MeV neutron activation analysis. The (n, 2n) nuclear reactions are used for all elements except La, for which (n, p) reaction is used. Al is used as a flux monitor for the relative method and as a singlle comparator for the single comparator method. The analytical results obtained by the two methods agree well within 3% deviation except for Sm and Gd. These results are also compared with the result obtained by a single comparator method using reactor neutron.     

Uncertainty budget and validation of NAA using Reference Materials

Instrumental neutron activation analysis (INAA) has been used at the research reactor of the Institute of Nuclear Techniques for measuring different types of samples for many years. For standardization purposes, the single comparator method has been applied. Since the theoretical basis of NAA is well understood, the sources of uncertainty can be well estimated, detailed uncertainty calculations have been recently performed to meet the increasing demands for method validation. INAA was validated by the analyses of sets of reference materials (RM), selectivity was controlled, accuracy and precision of the method as well as linearity, detection limits and measuring ranges were determined. Under the conditions of QA/QC, NAA can meet the high demands of trace element analysis. This revised version was published online in August 2006 with corrections to the Cover Date.     

Study on the comparator method using substoichiometry

The comparator method using substoichiometry is developed. In the method, the contents of the elements can be determined simultaneously by the measurement of radioactivities of the comparator elements and of simultaneously separated parts of the elements in question. The method is applied to the simultaneous determination of rare earth elements, such as lanthanum, europium and terbium in NBS botanical standard reference materials. It is confirmed that the method is reliable for simultaneous multielement determination.     

Instrumental neutron activation analysis of silicon wafers using the silicon matrix as the comparator

For the instrumental neutron activation analysis of trace impurities in high purity silicon wafer, a modified single comparator method has been applied. The energy distribution of the neutrons at the irradiation position was measured using the two flux monitors, Au and Co, and elemental contents were calculated using the silicon matrix in the wafer as a comparator. This has advantage of reducing the cross contamination from an external monitor during sample preparation and irradiation, the uncertainties from the non-homogeneity of the neutron flux and the error on the weight of comparators. Determination limits for 49 elements were presented under the condition of 72 hours irradiation at a neutron flux of 3.7·10¹³ n·cm^-2·s^-1 and 4000 s measurement. The analytical results obtained by this method and the conventional single comparator method were compared and were found to agree well within 5%.     

Elemental composition of Thai rice and beans by instrumental neutron activation analysis

The nutrient value of Thai rice and bean in terms of minor and trace element content has been evaluated using INAA. Six varieties of rice and six of beans bought from three local markets in 2006–2007 were investigated under this study. Elemental compositions were determined using the comparator technique. Precision, accuracy and detection limits of each element found were also calculated. Three minor (Ca, K, Mg) and eight trace elements (Al, As, Br, Cl, Cu, Fe, Mn, Zn) were determined in these Thai foods.     

Activation analysis of high-purity silicon

The triple comparator method is used for the analysis of impurities of high purity silicon by neutron activation. The ratios of the specific photopeak activities of the isotopes investigated to the specific photopeak activities of the gold, indium and cobalt comparators were determined. The triple comparator method avoids some tedious problems in the multi-element activation analysis and it is very well suited for the determination of ‘non-expected’ elements. Research associate of the N. F. W. O.     

Automatic interpretation of gamma-ray data obtained in non-destructive activation analysis

The procedure in use at our institute for the extraction of the desired element concentrations in a sample from the peak data obtained by a spectrum analysis program, is described in detail. The method is based on the use of zinc as a single comparator and takes into consideration primary activation products as well as their daughter isotopes. After assigning isotopes to spectrum peaks on the basis of γ-ray energies, the list of possible isotopes is reduced to a list of present isotopes with their concentrations using criteria based on half life, specificity and intensity of γ-rays. For elements not observed, detection limits are estimated. The procedure has been used extensively during the last two years and has shown to produce reliable results.     

The use of universal comparator method in large-scale NAA

For simplicity and unification of the comparator methods it is proposed to obtain a calibrating function of changing relative efficiency of registrating -radiation for any geometry of measurement (for any detector) from -spectrum comparator isotopes directly. In determining elements by their short- and medium-lived radionuclides the comparators⁵²V and²⁴Na were used. Biisotope comparator (⁶⁵Zn,¹²²Eu or¹⁸²Ta) was used for long-lived radionuclides. The developed universal comparator method significantly simplifies the procedures for determining relative registration efficiencies of analytical lines of interesting radionuclides, thus reducing the labor and time requirements of analysis; this is very important in the case of a large scale NAA.     

The multiplication of errors due to the application of a relative multiple comparator method

The comparator method, earlier published byDe Corte et al. is first discussed as well as a more practical transformation, which delivers directly the flux ratio, using a relative technique. For each part of the multiple comparator method (MCM) separately, a discussion of error multiplication is worked out and at the end a general formula to calculate the total error change is derived. Research associate of the IWONL. Research associate of the NFWO.     

Elemental analysis of vegetation samples by INAA internal standard method

Journal of Radioanalytical and Nuclear Chemistry - The application of comparator instrumental neutron activation analysis (INAA) combined with the internal standard method (ISM) was considered to...     

Error estimation of the single comparator method due to uncertainties of literature data for thermal and epithermal neutron activation cross-sections

The reliability of the single comparator method depends mainly on the accuracy of k factors. This paper describes error in theoretical k factors, especially that due to the scattering in literature data for thermal and epithermal neutron activation cross-sections. Error calculations were performed for thirteen elements using comparator sets of⁶⁰Co−¹⁹⁸Au and⁹⁵Zr−⁹⁷Zr to evaluate the accuracy of this method.     

Application of the INAA methods for KRISS infant formula CRM analysis: standardization of INAA at KRISS

We have established an instrumental neutron activation analysis (INAA) method, including k₀-based INAA, at the Korea Research Institute of Standards and Science (KRISS) for the certification of reference materials. As part of establishing INAA measurements, KRISS infant formula certified reference material was analysed for multiple elements at three different metrological institutes: KRISS and NIST for the standard comparator method, and JSI for the k₀-INAA method. The mass fraction of most elements was consistent within expanded uncertainty (k?=?2). In addition, the results were used to verify the validity of elemental analysis of Zn using the standard comparator INAA at KRISS, and spreadsheet-based INAA calculations were evaluated.

     

重量法配气的称量数学模型及其不确定度评定

对重量法制备气体标准物质中充入气体质量的计算方法进行了研究,建立了基于单盘电子天平的钢瓶称量方法,并建立了系统的数学模型和不确定度评价方法。为重量法制备气体标准物质提供一种简单、实用和精确的钢瓶称量方法和气体加入质量的计算方法。     

Determination of antimony in tin by radiochemical neutron activation analysis

New types of correction for chemical yield and counting geometry in conjunction with the comparator method provide significant improvements in reproducibility and sensitivity compared to direct neutron activation analysis.