Analysis by neutron activation

Iieser et al. [628] studied the application of neutron activation analysis to the determination of trace elements in seawater. The rare earths included in this study were cerium and europium. The element concerned were adsorbed onto charcoal. Between 75% and 100% of the elements were adsorbed onto the charcoal which was then subjected to analysis by neutron activation analysis. Cerium (300 p,g/l) and europium (0.00082 pg/1) were found in North Sea water by this method. 

Perlman, I. and Asaro, F., Pottery Analysis by Neutron Activation, in Science and Archaeology. R. H. Brill, ed., MIT Press, Cambridge, Mass., Archaeometry 11, 21-52 (1969). 

Perlman, I. and Asaro, F. (1969). Pottery analysis by neutron activation analysis. Archaeometry 11 21-52. 

Analysis by Neutron Activation, Oxford University Press, Oxford, England, 1962. 

Anders, O. U., and D. W. Briden A Rapid, Non-destructive Method of Precision Oxygen Analysis by Neutron Activation. Anal. Chem. 36, 287 (1964). 

For analysis of lanthanide ions in complex matrices like rocks, it is generally necessary to remove non-lanthanide components of the dissolved sample before conducting the analysis. Preconcentration is often essential for lanthanide analysis by neutron activation, wherein the y-emission spectra of certain matrix elements overlap with those of the target lanthanides. In mass-spectrometric analysis of samples, some matrix elements can interfere with lanthanide quantitation (for example, barium with lanthanum). Application of a preseparation step gives the added benefit of concentrating dilute solutions of lanthanides to improve detection limits. 

The use of the rare earths as a geochemical tool began in the early I960 s with the development of techniques for their analysis by neutron activation, followed by methods of isotope dilution mass spectrometry. These techniques provided measurements of sufficient accuracy on common (but chemically complex) natural materials that the potential use of rare earth distributions could be recognized and put to use. Summaries of early work are given by Haskin and Frey (1966), Haskin et al. (1966a), and Herrmann (1968). 

Neutron Activation Analysis Few samples of interest are naturally radioactive. For many elements, however, radioactivity may be induced by irradiating the sample with neutrons in a process called neutron activation analysis (NAA). The radioactive element formed by neutron activation decays to a stable isotope by emitting gamma rays and, if necessary, other nuclear particles. The rate of gamma-ray emission is proportional to the analyte s initial concentration in the sample. For example, when a sample containing nonradioactive 13AI is placed in a nuclear reactor and irradiated with neutrons, the following nuclear reaction results. 

Determination of gold concentrations to ca 1 ppm in solution via atomic absorption spectrophotometry (62) has become an increasingly popular technique because it is available in most modem analytical laboratories and because it obviates extensive sample preparation. A more sensitive method for gold analysis is neutron activation, which permits accurate determination to levels < 1 ppb (63). The sensitivity arises from the high neutron-capture cross section (9.9 x 10 = 99 barns) of the only natural isotope, Au. The resulting isotope, Au, decays by P and y emission with a half-life of 2.7 d. 

The concrete block walls of the cell housing the generator tube and associated components are 1.7 meters thick. The facility also includes a Kaman Nuclear dual-axis rotator assembly for simultaneous transfer and irradiation of reference and unknown sample, and a dual Na iodide (Nal) scintillation detector system designed for simultaneous counting of activated samples. Automatic transfer of samples between load station to the rotator assembly in front of the target, and back to the count station, is accomplished pneumatically by means of two 1.2cm (i.d.) polyethylene tubes which loop down at both ends of the system and pass underneath the concrete shielding thru a pipe duct. Total one-way traverse distance for the samples is approx 9 meters. In performing quantitative analysis for a particular element by neutron activation, the usual approach is to compare the count rates of an unknown sample with that of a reference standard of known compn irradiated under identical conditions... 

Certification of Element Contents by Neutron Activation Analysis... 

Delfanti R, Di Casa M, Gallorini M, and Orvini E (1984) Five years activity in determining trace elements for the certification of standard reference materials by neutron activation analysis. Mikrochim Acta [Wien] L239-250. 

Kucera j (1995) Elemental characterization of new Polish and US NIST geological, environmental and biological reference materials by neutron activation analysis and comments on the methodology of interlaboratory comparisons. Chem Anal (Warsaw) 40 405-421. 

An inscribed thick plate of brass attributed to the landing, in 1579, of Francis Drake on the coast of California, is retained in safekeeping at the University of California, Berkeley. Since its discovery, in the San Francisco Bay area in 1936, however, there have been doubts about the authenticity of the plate, although an early chemical study had apparently confirmed its authenticity. Regardless of this initial study, doubts about the origin of the plate persisted, and a new study, based on the composition of the brass as determined by neutron activation, X-rays fluorescence, and atomic absorption analysis was initiated to reevaluate the earlier authentication of the plate. The results of this study were then compared with the composition typical of brass from Drake s time as well as from modem brass, and it was then concluded that the plate was probably made during the latter part of the nineteenth century or the early years of the twentieth century (Hedges 1979). 

Yusov et al. [67] separated arsenic (III) and arsenic (V) in seawater using a chloroform solution of ammonium pyrrolidine diethyldthiocarbamate. The separated fractions were then analysed by neutron activation analysis. 

After adjusting to 2 mol 1 1 in hydrochloric acid, 500 ml of the sample is adsorbed on a column of Dowex 1-XS resin (Cl form) and elution is then effected with 2 M nitric acid. The solution is evaporated to dryness after adding 1M hydrochloric acid, and the tin is again adsorbed on the same column. Tin is eluted with 2 M nitric acid, and determined in the eluate by the spectrophotometric catechol violet method. There is no interference from 0.1 mg of aluminium, manganese, nickel, copper, zinc, arsenic, cadmium, bismuth, or uranium any titanium, zirconium, or antimony are removed by ion exchange. Filtration of the sample through a Millipore filter does not affect the results, which are in agreement with those obtained by neutron activation analysis. 

The average concentration and standard deviation of the Pacific Ocean waters ( xg/l) were 2.00 0.09 by neutron activation analysis, and 1.86 0.12 by atomic absorption spectrometry. For the Adriatic water the corresponding values were about 1.7 xg/l. The difference between the values for the same seawater is within the range to be expected from the standard deviations observed. 

Stiller et al. [824] have described the determination of cobalt, copper, and mercury in Dead Sea water by neutron activation analysis followed by X-ray spectrometry and magnetic deflection of /i-ray interference. 

Holzbecker and Ryan [825] determined these elements in seawater by neutron activation analysis after coprecipitation with lead phosphate. Lead phosphate gives no intense activities on irradiation, so it is a suitable matrix for trace metal determinations by neutron activation analysis. Precipitation of lead phosphate also brings down quantitatively the insoluble phosphates of silver (I), cadmium (II), chromium (III), copper (II), manganese (II), thorium (IV), uranium (VI), and zirconium (IV). Detection limits for each of these are given, and thorium and uranium determinations are described in detail. Gamma activity from 204Pb makes a useful internal standard to correct for geometry differences between samples, which for the lowest detection limits are counted close to the detector. 

Differentiation of inorganic and organic mercury can be achieved in a number of different ways, many of which depend upon the reduction and vapourisation of the inorganic mercury, followed by reduction [84] or oxidation [85,86] of the organic mercury compounds, and a final measurement by atomic absorption or mass spectrometry. Similar methods of separation of the inorganic and organic components are used in the pretreatment of samples where the final analysis for mercury is to be made by neutron activation analysis [87,88]. 

Nadkami, R.A. and W.D. Ehmann. 1970. Trace element determination in biological materials by neutron activation analysis. Pages 407-419 in D.D. Hemphill (ed.). Trace Substances in Environmental Health IV. Univ. Missouri, Columbia. 

Glascock, M.D. (1992). Characterization of archaeological ceramics at MURR by neutron activation analysis and multivariate statistics. In Chemical Characterization of Ceramic Pastes in Archaeology, ed. Neff, H., Prehistory Press, Madison, Wisconsin, pp. 11-26. 

Tsolakidou, A. and Kilikoglou, V. (2002). Comparative analysis of ancient ceramics by neutron activation analysis, inductively coupled plasma-optical emission spectrometry, inductively coupled plasma-mass spectrometry, and X-ray fluorescence. Analytical and... 

It is seen by examination of Table 1.11(b) that a wide variety of techniques have been employed including spectrophotometry (four determinants), combustion and wet digestion methods and inductively coupled plasma atomic emission spectrometry (three determinants each), atomic absorption spectrometry, potentiometric methods, molecular absorption spectrometry and gas chromatography (two determinants each), and flow-injection analysis and neutron activation analysis (one determinant each). Between them these techniques are capable of determining boron, halogens, total and particulate carbon, nitrogen, phosphorus, sulphur, silicon, selenium, arsenic antimony and bismuth in soils. 

Until it was known that the half-life of Tc is much shorter than 10 years Herr looked for technetiimi-98 in a munber of minerals from Norway and South Africa by neutron activation analysis. This most sensitive method was also used by Alperovitch et al. and Anders et al. to detect this isotope in nature. According to the nuclear reaction... 

A technique for the determination of Tc amounts as little as 4 x 10 g by neutron activation analysis has been described by Foti et al. . Tc in triply distilled water is irradiated in a thermal neutron flux of 5 x 10 neutrons per cm and per second to produce °°Tc. Other radionuclides are removed by co-precipi-tation with Fe(OH)j. Then, °°Tc is co-precipitated twice with tetraphenylarsonium perrhenate which can be removed by sublimation. The chemical purification of °°Tc requires 40-45 s and the technetium yield is about 53%. 

Trace amounts of Tc are also determined in filter paper and vegetable samples by neutron activation analysis The procedure consists of the following major steps separation of technetium from the sample, thermal neutron irradiation of the Tc fraction to produce °°Tc, post-irradiation separation and purification of °°Tc from other activated nuclides, and counting of the 16 s Tc in a low-background P counter. The estimated detection limits for Tc in this procedure are 5 x 10 g in filter paper and 9 x 10 g in vegetable samples. 

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