Instrumental NAA

If a solid-state Ge(Li) detector and a 1000- to 4000-channel analyzer are available, instrumental NAA can be extended to many elements. For example, Rancitelli (6) has analyzed coal and fly ash for 25 major, minor, and trace elements by using instrumental NAA with computer data reduction. Block and Dams (7) used similar analysis and reported on 43 elements in coal. Clearly, this is a good method for rapidly monitoring the composition of many coal samples. 

Weaver and von Lehmden (20), under sponsorship of the EPA, evaluated two instrumental NAA methods and one with radiochemical separation for determining mercury in coal. 

Kucera et al. [161] performed a comparative analysis of three procedures for determining I in food. Their accuracy and precision were checked against reference materials based on food products. The limit of detection was 1 pg/kg. Instrumental NAA (INAA) and replicate sample INAA (RSINAA) were used in Portugal to test a wide assortment of food products for their total Se content [162], INAA and radiochemical NAA (RNAA) were also used to assess the quality of bottled water sold in Greece [163]. Elements such as U, Ba, La, Sb, Ca, Cr, Zn, K, As, Br, Se and... 

River sediments None Instrumental NAA No data VO (certified materials) Labrecque et al. 1986... 

Air samples Sample collection on filters Instrumental NAA 2 ng/sample 95 Landsberger and Wu 1993... 

The NAA method can be divided into NAA (Instrumental NAA) and RNAA (Radiochemical NAA). In the latter, the various neutron-induced products are separated chemically to minimize interferences. There are several comprehensive review papers on INAA published in the literature 1,2,3,4). Briefly, the basic parameters controlling sensitivity for a multi-element determination are neutron flux, irradiation time, delay interval prior to counting, half-life and gamma-ray energy of the induced activity, and eflBciency and resolution of the detector. Table I outlines the irradiation parameters used for each of the two sequential irradiations. The final count occurring 40-50 days after the second irradiation is performed on an anti-coincidence-shielded Ge(Li) system developed recently in our laboratory. 

Material Stone - Marble Instrumentation NAA elemental analysis Application Authentication/Provenience Place Greece and Los Angeles Time Period Classic Greece, 600-300 bc... 

The facilities required for NAA and the obvious problems associated with either chemical separations or the spectral interferences in the instrumental NAA methods make this technique impractical for most investigators. Also the NAA cannot be classified as a definitive or reference method since there are obvious interferences such as phosphorus which require some correction factor. 

Table 7 lists a very limited selection of NAA procedures for Cr in various biological matrices, either by instrumental NAA (I NAA) or after radiochemical separations. In both... 

Both instrumental NAA (INAA) and PIXE are available at the Instituto Tecnol6-gico e Nuclear (ITN), Sacavem, Portugal, and have been applied in a national study on atmospheric trace elements, using lichens as biomonitor materials. In the present paper, this survey is used to illustrate the potential of NATs in environmental studies. 

In activation analysis advantage is taken of the fact that the decay properties such as the half-life and the mode and energy of radioactive decay of a particular nuclide serve to identify uniquely that nuclide. The analysis is achieved by the formation of radioactivity through irradiation of the sample either by neutrons or charged particles. Neutron irradiation is by far the more common technique, and hence this method is often referred to as neutron activation analysis, NAA. A major advantage in activation analysis is that it can be used for the simultaneous determination of a number of elements and complex samples. If the counting analysis of the sample is conducted with a Ge-detector and a multichannel analyzer, as many as a dozen or more elements can be measured quantitatively and simultaneously (instrumental NAA, or INAA). 

Many authors have used the sensitive technique of NAA to determine W in various biological samples such as blood, urine, toenail, pubic hair, lung biopsy and bronchoalveolar lavage effluent [7,8], bone [39], tooth [40], and heart [41]. Toenails and pubic hair have been analyzed by instrumental NAA whereas the other systems have been studied by radiochemical NAA. 

The concentrations of Br, Ca, Cl, Co, Cu, K, Mg, Mn, Na, and V in cereals, oils, sweeteners, and vegetables sold in Canada were determined with absolute instrumental NAA. These items also indicated the presence of 1, Rb, S, and Ti (Soliman and Zikovsky 1999). 

The NAA technique can be broadly classified into two categories based on whether chemical separations are employed in the analytical procedure. Under favourable conditions, the experimental parameters such as irradiation, decay and counting times can be optimized so that the elements of interest can be determined without the need of physical destruction of the sample by chemical treatments. This process is called non-destructive NAA. However, it is more commonly referred to as instrumental NAA (INAA) and is the most widely used form of NAA. 

Neutron activation analysis (NAA) is one of the most important nuclear techniques for nanometallome quantification, as it can simultaneously measure more than 30 elements in a sample. The detection limits of NAA range from 10 to 10 gg In typically instrumental NAA, stable nuclides ( Z, the target nucleus) in the sample undergo neutron capture reactions in a flux of (incident) neutrons. The radioactive nuclides the compound nucleus)... 

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