Neutron activation analysis quantification

Some of the methods commonly used for the determination of thorium in biological materials are given in Table 6-1. The colorimetric methods are not capable of isotope-specific determination of thorium isotopes. Alpha spectrometric and neutron activation analysis are useful in the quantification of isotope-specific thorium and thorium-232, respectively, and have better sensitivities than colorimetric methods. Alpha spectrometry is the commonly used isotope-specific analysis for the determination of thorium-232 and the thorium-230 derived from the decay of uranium-238 (Wrenn et al. 1981). Standard reference materials (SRMs) containing thorium in human liver (SRM-4352) and human lung (SRM-4351) necessary for the determination of absolute recovery in a given sample are available from the National Institute of Standards and Technology (Inn 1987). 

The principal methods used for detection and quantification of antimony in biological and environmental samples are various modifications of neutron activation analysis (NAA) and atomic absorption spectrometry (AAS) (ATSDR 1992). AAS techniques (including matrix modification, hydride-formation and flameless AAS) - eventually after enrichment - have proved especially... 

In order to evaluate possible hazards for the enviroiunent and human health it is crucial to develop analytical strategies for fast and easy quantification of traces and ultra-traces of Pd in environmental matrices as well as biological tissues and fluids. Despite the efforts of numerous workgroups, a reliable method for the determination of Pd in all environmental matrices has yet to be developed. Up to date, the most important analytical methods for this task are electrothermal atomic absorption spectrometry (ETAAS), inductively coupled plasma-mass spectrometry (ICP-MS) and isotope dilution (ID)-ICP-MS, also strategies involving inductively coupled plasma-atomic emission spectrometry (ICP-AES), and electrochemical methods like anodic stripping voltammetry (ASV) have been described. Furthermore, total reflection X-ray fluorescence (TXRF) and instrumental neutron activation analysis (INAA) have been successfully employed for the determination of PGE in enviromnental matrices. 

Negi, B. S., V. Meenakshy T. M. Krishnamoorthy, 1997. Kq method of quantification in neutron activation analysis as applied to environmental samples. Envir. Monit. Assess. 47 303-313. 

Neutron activation analysis (NAA) is also a multielemental quantification technique which can simultaneously measure more than 30 elements in a sample. The detection limits of NAA range from 10 to 10 gg dependent upon the irradiation parameters, measurement eonditions, and nuclear parameters of the elements of interest. It has been mueh used in many areas of fundamental and applied researeh as well as industrial applieations. The theme... 

In this section only the most recent methods (post 1990) for extraction and quantitative determination of PCAs in commercial products and environmental samples are discussed. While extraction and isolation techniques have relied mainly on techniques already developed for POPs, there have been major advances in the quantification of PCAs using gas chromatography mass spectrometry in electron capture negative ionization mode (GC-ECNIMS). No attempt will be made to discuss older methods of analysis such as thin-layer chromatography [13,50], and neutron activation methods [51]. 

NAA is a quantitative method. Quantification can be performed by comparison to standards or by computation from basic principles (parametric analysis). A certified reference material specifically for trace impurities in silicon is not currently available. Since neutron and y rays are penetrating radiations (free from absorption problems, such as those found in X-ray fluorescence), matrix matching between the sample and the comparator standard is not critical. Biological trace impurities standards (e.g., the National Institute of Standards and Technology Standard Rference Material, SRM 1572 Citrus Leaves) can be used as reference materials. For the parametric analysis many instrumental fiictors, such as the neutron flux density and the efficiency of the detector, must be well known. The activation equation can be used to determine concentrations ... 

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