Advantages of NAA

Activation analysis measures the total amount of an element in a material without regard to chemical or physical form and has the following advantages  

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One of the important advantages of NAA is its applicability to almost all elements in the periodic table. Another advantage of neutron activation is that it is nondestructive. Consequently, NAA is an important technique for analyzing archaeological and forensic samples, as well as works of art. 

Most of the transition elements that are of primary interest in the semiconductor industry such as Fe, Cr, Mn, Co, and Ni, can be analyzed with very low detection limits. Second to its sensitivity, the most important advantage of NAA is the minimal sample preparation that is required, eliminating the likelihood of contamination due to handling. Quantitative values can be obtained and a precision of 1-5% relative is regularly achieved. Since the technique measures many elements simultaneously, NAA is used to scan for impurities conveniently. 

Unstable radionuclei result on subjecting the nuclei of some elements to neutron bombardment. During the decay process, in which the radionuclei return to more stable forms, characteristic radiation is emitted. The energy of the radiation is characteristic of the element, and its intensity forms the basis for quantitative elemental analysis. The advantages of NAA for trace analysis include low detection limits, good sensitivity, multi-element capability and relative freedom from matrix effects. However, for successful application of this technique skilled personel are required and because of the low sample throughput the amount of work involved in the analysis of column fractions, for example, is prohibitively high. In addition, it may take up to several weeks before the results are available. Further, only few laboratories have easy access to a neutron source. 

Because neutron activation analysis of zinc appeared to require little sample preparation and Is capable of better precision than GC/MS, It was the method of analysis selected for our first experiment. Separation of zinc from other minerals In the samples was required, however, eliminating this as an advantage of NAA. Precision of this method was not as good In our experiment as had been expected. 

Neutron Activation Analysis This technique permits the quantitative and qualitative identification of elements. It is based on the conversion of a stable atomic nucleus into a radioactive nucleus by bombarding it with neutrons. The radiation emitted by the radioactive nuclei is then measured [154]. The advantages of NAA include [16, 154] ... 

Of the nuclear analytical techniques, NAA is the most important for iodine determination in foodstuffs. The main advantage of NAA is the ultimately low detection limit, which can be achieved using RNAA or PS-NAA, nondestructive performance of INAA and EINAA, freedom from interference and matrix effects of all modes of NAA for the determination of total iodine content. 

One of the most important advantage of NAA is that it is nearly free of any matrix interference effects because the atoms of matrix are composed of H, C, O, N, P, and Si that do not form any radioactive isotopes. This makes the method highly sensitive for measuring trace elements. Thus the vast majority of samples are completely transparent to both the probe (the neutron) and the analytical signal (the y-ray). 

The information on the chemical speciation of trace elements in biological systems is much needed to evaluate their biological significance. Although a number of analytical techniques based on atomic behavior are available for the analysis of chemical speciation of trace elements, neutron activation analysis, as a nuclear analytical technique, can be successfully used in chemical speciation studies, after appropriate fractionation steps. Table 2.5 lists some typical applications of NAA in chemical speciation analysis of metalloproteins. The main advantages of NAA are of its high sensitivity and the absence of matrix effects inherited from the conventional neutron activation analysis. It can, therefore, be used to analyze the chemical species of trace elements in very small samples or complicated matrices, which is often impossible for non-nuclear techniques. 

The increase in accuracy afforded by a radiochemical separation is absolutely necessary in the determination by NAA of trace elements in the coals selected as standards. The fact that interferences from the coal matrix are removed by a radiochemical separation is the advantage of this method of analysis over such instrumental methods as x-ray fluorescence and emission spectroscopy. 

Neutron activation analysis (NAA) technique has also been used for determining low levels of barium in human blood (Olehy et al. 1966). This technique is based on the interaction of the nuclei of individual barium atoms with neutron irradiation, resulting in the emission of x-rays (photons). Detection limits of 7 pg barium/L of erythrocyte and 66 pg barium/L of plasma were obtained (Olehy et al. 1966). The advantages of the NAA technique are its nondestructive nature of sample and minimum sample manipulation. Disadvantages of this technique include its high costs and a nuclear reactor may not be readily available to many laboratories. 

NAA, however, is not only able to avoid such problems, but also is more sensitive than traditional chemical analysis. In addition, neutron analysis has the advantage of being a nondestructive process over chemical analysis. NAA has been well-developed and widely accepted for trace iodine analyses of naturally existing stable (Akhter et aL, 2004 ... 

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