新型中空卤化银颗粒乳剂的制备和性能研究 Ⅱ.中子活化分析测定感光乳剂的元素组成

一般采用化学滴定法来定量分析卤化银乳剂中的银和卤素组份。其他仪器分析,如X射线能谱,X射线电子能谱,X光萤光等只能做到半定量或定性分析。而化学滴定法的实验操作步骤又十分繁琐,而且卤素的化学性质相近,需用差减法分别得到最后结果。本文采用中子活化分析法,样品不需预处理(即不需要去除明胶),即可对卤化银乳剂同时进行元素测定。所测定的数值与化学滴定法的结果对照比较,两者十分相近。说明利用中子活化分析来测定卤化银乳剂的元素组份是可靠的方法.     

Evaluation of <Superscript>40</Superscript>K in vegetables collected Malaysia by determination total potassium using neutron activation analysis

Some vegetables of important nutritive requirements have been collected from Kuala Lumpur region capital of Malaysia. The vegetables were analyzed in order to determine activity concentration level of potassium using neutron activation analysis (NAA). The NAA results obtained showed the activity concentration of ⁴⁰K varied from 379 Bq/kg (Egg-plant) to 1585 Bq/kg (Spinach Red). These results are compared to other researches and are clear that the concentrations of K are relatively high in the Malaysia in compared to rather than vegetables of Pakistan and Jamaican. However, they are seen not to pose any serious internal health burden due to ingestion given the realities of vegetables choice by individuals in the study area.     

Instrumental neutron activation analysis limits of detection in the presence of interferences

Many tables of neutron activation analysis (NAA) limits of detection, in the absence of interferences, for various irradiation and counting conditions, may be found in the literature. This paper presents a method for estimating, in advance, the instrumental NAA limits of detection for any elements of interest in any given matrix, including ones generating high interference levels. The rationale of the method is presented, and the procedure for applying it is illustrated.     

Challenges for INAA in Studies of Materials from Advanced Material Research Including Rare Earth Concentrates and Carbon Based Ceramics

Rare-earth elements are increasingly applied in advanced materials to be used, e.g., in electronic industry, automobile catalysts, or lamps and optical devices. Trace element analysis of these materials might be an interesting niche for NAA because of the intrinsic high accuracy of this technique, and the shortage of matrix matching reference materials with other methods for elemental analysis. The carbon composite materials form another category of advanced materials, where sometimes a very high degree of purity is required. Also for these materials, NAA has favorable analytical characteristics. Examples are given of the use of NAA in the analysis of both categories of materials.     

Comparison of the role of photon and neutron activation analyses for elemental characterization of geological,biological and environmental materials

The potential of photon activation analysis (PAA) for multielement trace analysis can hardly compare with that of neutron activation analysis (NAA). However, PAA appears superior over NAA for the determination of a number of elements, namely C, N, O, F, Mg, Si, Ca, Ti, Ni, Sr, Y, Zr, Nb, Sn, Tl and Pb in geological, environmental and biological materials. Most of these and other elements can be determined using nondestructive, instrumental PAA (IPAA), especially in geological materials. The possibilities of IPAA for multielement analysis using photoexitation and other photonuclear reactions are reviewed and compared with those of instrumental NAA (INAA), namely for geological materials. The need for and usefulness of radiochemical PAA (RPAA) procedures are also discussed.     

The NAA method at Polytechnique Montreal: an efficient alternative way to use the k 0 NAA models

At Ecole Polytechnique Montreal, the philosophy in performing neutron activation analysis (NAA) is long-term and application oriented. Thinking long-term implies a good understanding of the fundamentals of the method, of the samples, of the tools, reactor and detectors, and there must be constant innovation that is experimentally validated with extensive measurements. Application oriented means a NAA method developed to provide users with fast, sensitive, accurate and reliable analyses for various types of materials. This philosophy dictates the manner in which the developments in the areas of NAA software, peak-area calculation, dead-time correction, detection efficiency model, k ₀ and Q ₀ values, neutron moderation and neutron self-shielding are carried out. This paper presents a survey of the Laboratory’s methodology, reviewing a few of its unique features such as detector efficiency calibration and sample related perturbations of the neutron activation. These features are used as examples to provide the reader with an understanding of the philosophy and the evolution of the NAA method at Ecole Polytechnique.     

From misconception to a must: The measured merits of total quality management and accreditation in INAA

Increasingly govemmental bodies and industry require that supporting analytical laboratories have their quality assurance program implemented in a quality system by international standards such as derived from the ISO-25 guide. Neutron activation analysis (NAA) laboratories may have to deal with this trend too. In universities and research laboratories the need for it, and the implications of total quality management system are sometimes misconceived by unfamiliarity with the issue. The laboratory for INAA in Delft has been accredited for its quality system since 1993. Some of the tangible improvements since the introduction of quality management are presented. Four strategical considerations are given to consider the introduction of quality management at NAA laboratories, viz. with respect to the role of NAA for the validation of other methods, the role of NAA in the certification of reference materials, the preservation of knowledge and the acceptance of NAA as a respectable method.     

Nuclear activation methods for the characterization of fossil fuels

A review is presented on the use of neutron activation analysis (NAA) for the analyses of coal, oil shale, tar sands and petroleum. Fast NAA has been widely used for the determination of oxygen, and to a limited extent, of other elements such as nitrogen and silicon. Reactor NAA followed by instrumental counting, and in specific cases, after radiochemical separations is discussed. Thermal and epithermal neutrons are both used. Limited use of the²⁵²Cf source has been made in fuel analysis. A complementary technique to NAA is the photon-activation analysis with linear accelerator. It can determine over thirty elements, many of them not possible to do by NAA. Round-robin analyses of standard coal, fly ash, or oil shale samples indicate nuclear activation methods are comparable in accuracy and precision to X-ray fluorescence or atomic spectrometric methods for most elements.     

Further studies in the advance prediction of gamma-ray spectra and detection limits in instrumental neutron activation analysis

This computational procedure, described earlier for NaI(Tl) gamma-ray spectrometry, has now been set up for Ge(Li) spectrometry measurements, has been extended further in various details, has been partially computerized, and has been tested experimentally on both biological and geochemical types of samples—with good results. The procedure enables one to compute, in advance of any activations, the approximate Ge(Li) pulse-height spectrum of a sample for any selected flux and irradiation, decay, and counting times —and to compute the lower limits of instrumental NAA detection of any trace elements of interest—if the principal composition of the matrix is known. Various other useful parameters are also readily calculated.     

Gamma spectrum analysis including NAA with SAMPO for windows

SAMPO for Windows is a high performance gamma spectrum analysis program. All the measurement, analysis and NAA phases can be done either under full interactive user control or user defined tasks can be used for automated measurement and analysis sequences including control of MCAs and sample changers. High resolution gamma-ray spectroscopy together with the possibility to resolve complex multiplets with high accuracy makesSAMPO very suitable for INAA. On the other hand, the possibility to automate analysis sequences allows its use effectively also in all routine NAA measurements.NAA inSAMPO is accomplished using comparative methods. Spectra of standards, flux monitors, controls and actual samples are analyzed normally to obtain the peak areas which are optionally corrected for decay. In the comparison the flux monitor results are used to correct for variations in the effective neutron flux. An optional irradiation position correction can also be applied. The controls are used to alarm for possible deviations in the results.The sophisticated spectrum analysis methods used together with the comparative NAA and monitors give accurate results limited by the systematic effects only. The Windows environment provides ease of use and further processing power is available through the interface to expert system identification of nuclides.     

The state of nuclear archaeology in North America

We address three main topics in this paper. First, we briefly review the history of neutron activation analysis (NAA) as an archaeological tool in the United States and Canada. Second, we assess the current potential for undertaking NAA in North America. Third, we comment on methodological and technical issues in archaeometric NAA that are raised by other papers included in this special section.     

Optimization of information properties of NAA with respect to information content and profitability of results

Information properties of analytical results together with other important parameters especially economic ones can be used for the optimization of analytical procedures. Therefore, we have proposed a computational technique for the optimization of multielement neutron activation analysis (NAA) based on the information content and profitability. The optimization starts with the prediction of the -ray spectra to be expected during analysis under given experimental conditions (sample size, irradiation, decay and counting times etc.) and with the calculation of detection and determination limits. In the next step, the information contents for the determination of particular elements and for the simultaneous determination of element groups are computed. The information content depends or is closely connected with such properties of the method as selectivity, sensitivity, precision, accuracy and, as in the other cases of trace analysis, also with the detection limit. Then, the information profitability (IP) taking into account the information content and relevance (appreciation of specific information according to its contribution to the solution of a given problem) together with economic aspects can be calculated. This function can be used for the optimization of a particular NAA procedure, for the mutual comparison of different variants of NAA and also for the comparison with other analytical methods. The use of information profitability for the optimization of NAA is shown on a practical example of the INAA analysis of urban particulate matter SRM 1648 produced by NBS (USA).     

Neutron Activation Techniques in Environmental Studies

The development over time in applications of nuclear activation techniques in environmental studies is critically reviewed. A vast majority of the work has been based on activation analysis using thermal and sometimes epithermal neutrons from nuclear reactors (NAA). Whereas radiochemical methods were frequently used until about 1975, the work reported more recently has mainly been multi-element studies based on instrumental NAA. The by far most successful application has been the analysis of aerosol samples, but considerable work has also been done in other areas such as precipitation and surface waters, soils, vascular plants, moss and lichen biomonitors, and fossil fuels with by-products. Some interesting examples of speciation analysis, based on pre-irradiation separations, have also been reported. Rapid development in alternative multi-element techniques such as ICP-MS has shown these techniques to be superior in a number of cases where NAA earlier was the technique of choice. Areas where efforts should be concentrated in future NAA work are indicated.     

Multielemental Analysis of Solid Wastes and Leachates

During the past decade there has been a great emphasis on using multielemental methods to determine heavy metals in solid waste products arising from various industrial, combustion, municipal and mining activities. Furthermore, the study of the leaching characteristics of these solid wastes is of prime importance for environmental and regulatory considerations. We present an overview of neutron activation analysis (NAA), X-ray fluorescence (XRF) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) for the analysis of solid wastes and leachates. In particular we discuss several matrix problems that are usually not considered in routine NAA measurements.     

Neutron activation analysis of bulk samples from Chinese ancient porcelain to provenance research

Neutron activation analysis (NAA) is an important technique to determine the provenance of ancient ceramics. The most common technique used for preparing ancient samples for NAA is to grind them into a powder and then encapsulate them before neutron irradiation. Unfortunately, ceramic materials are typically very hard making it a challenge to grind them into a powder. In this study we utilize bulk porcelain samples cut from ancient shards. The bulk samples are irradiated by neutrons alongside samples that have been conventionally ground into a powder. The NAA for both the bulk samples and powders are compared and shown to provide equivalent information regarding their chemical composition. Also, the multivariate statistical have been employed to the analysis data for check the consistency. The findings suggest that NAA results are less dependent on the state of the porcelain sample, and thus bulk samples cut from shards may be used to effectively determine their provenance.     

Occupational nuclear medicine: Trace element analysis of living human subjects

Summary Several trace elements are toxic when present in excessive amounts. Such overloads occur most commonly in the occupational setting, although some environmental exposures are also of concern. The relationship between chronic exposure and health effects is best explored with the aid of knowledge of the quantity of element in question stored in the body. In vivo elemental analysis can provide this knowledge non-invasively for a number of elements of toxicological importance. In vivo analysis presents specific challenges, particularly the fact that the body is an extended medium, giving rise to extensive scattering and absorption. Also of primary importance, the radiation dose must be kept as low as reasonably possible and must in every case be within the range of other diagnostic procedures. Both the incident radiation and the detected signal must have an adequate mean free path in human tissue. This means that neutron activation analysis (NAA) and X-ray fluorescence (XRF) are the two most studied techniques. For some elements, analytical methods are established while others are under active development. For still others, no promising technique is currently available. The most fully developed techniques are for lead and cadmium. For lead three different XRF approaches have been put forward, although one, ¹⁰⁹Cd excited K XRF is most widely used. For cadmium, both prompt gamma NAA and XRF have been developed to the extent of full human studies. Amongst elements for which application to human studies has begun or is likely to begin shortly are aluminum and manganese, both using NAA.     

Review of neutron activation analysis in the standardization and study of reference materials, including its application to radionuclide reference materials

Summary Neutron activation analysis (NAA) plays a very important role in the certification of reference materials (RMs) and their characterization, including homogeneity testing. The features of the method are briefly reviewed, particularly aspects relating to its completely independent nuclear basis, its virtual freedom from blank problems, and its capacity for self-verification. This last aspect, arising from the essentially isotopic character of NAA, can be exploited by using different nuclear reactions and induced nuclides, and the possibility of employing two modes, one instrumental (nondestructive), the other radiochemical (destructive). This enables the derivation of essentially independent analytical information and the unique capacity of NAA for self-validation. The application of NAA to quantify natural or man-made radionuclides such as uranium, thorium, ²³⁷Np, ¹²⁹I and ²³⁰Th is discussed, including its advantages over conventional radiometric methods, and its usefulness in providing independent data for nuclides where other confirmatory analyses are impossible, or are only recently becoming available through newer atom counting techniques. Certain additional, prospective uses of NAA in the study of RMs and potential RMs are mentioned, including transmutation reactions, creation of endogenously radiolabelled matrices for production and study of RMs (such as dissolution and leaching tests, use as incorporated radiotracers for chemical recovery correction), and the possibility of molecular activation analysis for speciation.     

Application of different activation analysis techniques for determination of trace elements in human blood

One of the requirements of stable isotope tracer technique is detection of two isotopes of same element. It is preferable to use instrumental techniques in order not to contaminate the samples. Different instrumental nuclear techniques namely neutron activation analysis (NAA), photon activation analysis (IPAA), and prompt gamma ray activation analysis (PGAA) were tried on human blood samples. The techniques were found to be complementary to each other, NAA being the most sensitive of the three. Zinc is choosen for validation work among the three feasible elements (Zn, Cr, Se) for stable isotope tracer technique. As NAA was not sufficient to detect two isotopes of Zn, a radiochemical separation scheme was developed later.     

NAA and UV Laser Ablation ICP-MS for Platinum Group Elements and Gold Determination in NiS Fire Assay Buttons: A Comparison between Two Methods

NAA and UV laser ablation ICP-MS were used to determine platinum group elements (PGEs) and gold in the geological reference materials UMT-1, WPR-1, WMG-1, GPT-4 and GPt-6, after NiS fire assay. Both methods presented results were good agreement with the recommended values. NAA gave more accurate values for Ir (relative errors between 0 to 9%) and UV-LA-ICP-MS presented better results for Pt (relative errors less than 12%, except for WPR-1). UV-LA-ICP-MS showed better sensitivity than NAA for Pd and Os. On the other hand, NAA showed lower detection limits for Ir and Au. Advantages and disadvantages of each method are discussed.