Instrumental neutron activation analysis sensitivity

Atomic absorption spectroscopy of VPD solutions (VPD-AAS) and instrumental neutron activation analysis (INAA) offer similar detection limits for metallic impurities with silicon substrates. The main advantage of TXRF, compared to VPD-AAS, is its multielement capability AAS is a sequential technique that requires a specific lamp to detect each element. Furthermore, the problem of blank values is of little importance with TXRF because no handling of the analytical solution is involved. On the other hand, adequately sensitive detection of sodium is possible only by using VPD-AAS. INAA is basically a bulk analysis technique, while TXRF is sensitive only to the surface. In addition, TXRF is fast, with an typical analysis time of 1000 s turn-around times for INAA are on the order of weeks. Gallium arsenide surfaces can be analyzed neither by AAS nor by INAA. 

With analytical methods such as x-ray fluorescence (XRF), proton-induced x-ray emission (PIXE), and instrumental neutron activation analysis (INAA), many metals can be simultaneously analyzed without destroying the sample matrix. Of these, XRF and PEXE have good sensitivity and are frequently used to analyze nickel in environmental samples containing low levels of nickel such as rain, snow, and air (Hansson et al. 1988 Landsberger et al. 1983 Schroeder et al. 1987 Wiersema et al. 1984). The Texas Air Control Board, which uses XRF in its network of air monitors, reported a mean minimum detectable value of 6 ng nickel/m (Wiersema et al. 1984). A detection limit of 30 ng/L was obtained using PIXE with a nonselective preconcentration step (Hansson et al. 1988). In these techniques, the sample (e.g., air particulates collected on a filter) is irradiated with a source of x-ray photons or protons. The excited atoms emit their own characteristic energy spectrum, which is detected with an x-ray detector and multichannel analyzer. INAA and neutron activation analysis (NAA) with prior nickel separation and concentration have poor sensitivity and are rarely used (Schroeder et al. 1987 Stoeppler 1984). 

First, we analyzed samples for a large number of elements to Identify any elements, regardless of toxicity or typical concentration, that would provide signals for the presence of material from certain types of sources. Both ambient samples and particles from sources were analyzed by Instrumental neutron activation analysis (INAA), by which one can often measure about 35 elements In Individual samples (17), As the Important elements Pb, N1 and Cd are not consistently, If ever, observed by INAA, they were often measured by other methods. As INAA Is sensitive to very small amounts of obscure elements, we have obtained reliable data for elements such as Ga, Hf, Sc, In, W and many rare earths which pose no known health hazard at present levels and contribute Insignificant amounts of mass to TSP. However, as discussed below, many trace elements have already been shown to be Important In receptor... 

We have operated the University of Washington MKV impactor as a low-pressure impactor to provide for chemical analysis, four discretely sized fly-ash fractions in the sub-half-micrometer- diameter aerosol accumulation region. Instrumental neutron activation analysis provided the sensitivity to determine accurately the concentrations of 28 major, minor, and trace elements with sufficient precision to reveal fine structure in the elemental distributions that might be missed by techniques of lesser accuracy and precision. 

Quantitative trace element analysis of diamond by LA-ICP-MS using different synthetic multielement carbon based standards (e.g., cellulose pellets) is discussed by Rege et al 2, whereby 13C was used for internal standardization. Concentrations of 41 elements were determined in two fibrous diamonds from Jwaneng Botswana (JWA 110 and 115) by relative sensitivity coefficients measured using the synthetic cellulose standard. The analytical data were verified by means of instrumental neutron activation analysis (INAA) and proton induced X-ray emission (PIXE).72... 

Battelle has developed instrumental neutron activation analysis (INAA) techniques which permit very sensitive and accurate multielement analysis of approximately 40 elements in coal and fly ash. These techniques, which will be described in this work, form the basis for extensive environmental studies of the effluent from coal-powered generating facilities and other pollution sources. 

Trace elemental analysis of ancient ceramics has been proven a very useful tool for tracing the circulation of this material. Instrumental neutron activation analysis (INAA) was for years the analytical technique of choice to measure the composition of ceramics because of the large number of elements it could determine and its good sensitivity. Lately, a few publications have shown that laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) could provide similar results as INAA more quickly and at lower cost. A protocol has been developed to determine 51 elements using LA-ICP-MS and tested it on Wari period ceramics previously analyzed using INAA. We show how INAA and LA-ICP-MS analysis lead to the same conclusion in terms of sample groupings. 

Trace element studies of ceramics have been undertaken for the purpose of locating source regions for archaeological materials since the 1960s. While a number of techniques have been used for this purpose, by far the most common and most effective has been instrumental neutron activation analysis (INAA), largely due to its excellent sensitivity, precision, accuracy and the large number of elements it can measure simultaneously. 

The determination of 129I in low-level radioactive waste was accomplished by radioactive instrumental neutron activation analysis [3]. A different group reported the determination of both 129I and 127I by neutron activation analysis and inductively coupled plasma mass spectrometry [4]. The method was very rapid - a sample could be analysed in three minutes. However, interference from 129Xe resulted in limited sensitivity for 129I detection. 

EUTRON ACTIVATION ANALYSIS IS A VERY SENSITIVE TECHNIQUE for trace element determinations in various samples. If there are no elements that mutually interfere, the purely instrumental version of this method is often chosen for its established advantages such as accuracy, speed, sensitivity, simultaneous multielement determination, and sample preservation (1). For these reasons, instrumental neutron activation analysis (INAA) was applied to samples taken from a series of metal-working residues excavated at Tel Dan, Israel, from 1985 to 1986. 

To show that REE and other trace elements could be used to characterize soapstone formations, it was necessary to show that variations between geologic bodies were greater than those for soapstone samples found within the formation. For these studies instrumental neutron activation analysis (INAA) was used because of its sensitivity and preci-... 

The availability of high flux thermal neutron irradiation facilities and high resolution intrinsic Ge and lithium drifted germanium (Ge(Li)) or silicon (Si(Li)) detectors has made neutron activation a very attractive tool for determining trace elemental composition of petroleum and petroleum products. This analytical technique is generally referred to as instrumental neutron activation analysis (INAA) to distinguish it from neutron activation followed by radiochemical separations. INAA can be used as a multi-elemental method with high sensitivity for many trace elements (Table 3.IV), and it has been applied to various petroleum materials in recent years (45-55). In some instances as many as 30 trace elements have been identified and measured in crude oils by this technique (56, 57). 

Instrumental neutron activation analysis (INAA) is an extremely sensitive method for the determination of metals and metal isotopes. INAA has been used successfully by Nadkarni et al. (20A73), Jenkins et al. (1934) and Kubota (2214) to determine numerous inorganic constituents (elements and several elemental isotopes) in both tobacco and tobacco smoke (1933). The use of INAA for tobacco and tobacco smoke analysis has been accepted worldwide (1933). Tobacco is ideally suited for INAA because of its large abundance and variety of inorganic components. Tobacco is a readily available, easy-to-handle solid, it produces little gas during irradiation, and is rapidly assayed by INAA. The literature on the use of INAA in tobacco is very large because tobacco is often used as a model in non-tobacco-oriented... 

Several investigators have used neutron activation analysis (NAA) to determine the aluminium content of biological specimens both with and without some chemical processing. Instrumental neutron activation analysis involves the bombardment of a sample with neutrons and the measurement of the radioactivity induced by nuclear reactions. No chemical processing is required. Upon activation Al (100% isotopic abundance) forms the radioactive AI nuclide by a (n,y) reaction. There are a number of attractive features in this technique which include excellent sensitivity with relative independence from matrix effects and interferences. Also, there is relative freedom from contamination since the sample is analyzed directly with minimal handling. One major problem is the need to... 

Mercury concentrations in constructed and actual crude oil samples were measured using three analytical methods that were compared with respect to accuracy, precision, and detection limit. The combustion method (U.S. EPA 7473 hybrid) and a commercial extraction method (non-standard) were found adequate to provide a good combination of sensitivity and accuracy, while instrumental neutron activation analysis was found to suffer from interferences from elements other than mercury but typically in crude oil. In the combustion method, direct syringe injection of aliquots to the combustion chamber was found advantageous in that it minimized opportunities for loss of volatile mercury. 

Neutron activation analysis is a sensitive and versatile method of rock analysis, chiefly applicable to trace elements and capable of determining a large number of elements simultaneously without necessarily destroying the sample. There are two approaches. Instrumental neutron activation analysis (INAA) employs a powdered rock or mineral sample radiochemical neutron activation analysis (RNAA) involves the chemical separation of selected elements. The range of elements analysed is given in Table 1.5 and the methods are described in detail by Muecke (1980). 

Abstract This chapter presents the basic principles of activation analysis and details its different types. Emphasis is given to instrumental neutron activation analysis and radiochemical separations for the determination of trace and ultra-trace elements. Location sensitive analysis is also included. 

A modem technique for nitrogen detn is known as fast neutron activation analysis. Materials such as RDX are exposed to a high density fast neutron flux which converts the 14N content of the sample into unstable 13N. The N is detd by measuring the 13 N produced by the 14N (n, 2n) 13N reaction. This technique is extremely sensitive, but requires specialized instrumentation (Refs 44, 51 61)... 

Samarium may be analyzed by spectrographic and spectrophotometric methods. In solution, the trivalent samarium shows sharp and intense absorption bands at 362.5, 347.5 and 402.0 nm. Trace analysis may be carried out most accurately by flame AA, ICP-AES, ICP/MS and neutron activation analysis. ICP/MS is the most sensitive method. The metal and its insoluble salts may be solubilized by digestion with acids and diluted appropriately for most instrumental measurements. 

The concentration levels of most trace metals and metalloids lie below 1000 pg P . Therefore, the classical methods of analysis do not have the required sensitivity. Among the instrumental techniques that have been extensively used for the analysis of biological materials include, atomic absorption spectrometry, plasma emission spectrometry, anodic stripping voltammetry and neutron activation analysis. 

Neutron activation analysis (NAA) with a rapid radiochemical separation has been the method generally used in recent years, but requires substantial investment, has high operating cost and limited availability. Modem flameless atomic absorption (AAS) instruments provide sensitivity approaching that of NAA and offer a viable alternative for the detection of firearms discharge residue. 

Detection techniques of high sensitivity, selectivity, and ease of coupling with sample preparation procedures are of special interest for measuring PGM content in biological and environmental samples. ICP MS, electrothermal atomic absorption spectrometry (ET AAS), adsorptive voltammetry (AV), and neutron activation analysis (NAA) have fotmd the widest applications, both for direct determination of the total metal content in the examined samples and for coupling with instrumental separation techniques. Mass spectrometry coupled with techniques such as electrospray ionization (ESI) and capillary electrophoresis (CE) (e.g., ESI MS", LC ESI MS", LC ICP MS, CE MS", and CE ICP MS) offer powerful potential for speciation analysis of metals. MS is widely used for examination of the distribution of the metals in various materials (elemental analysis) and for elucidation of the... 

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