Activity analysis


High-current EC-50 betatron with maximal energy of accelerated electrons equaled to 50 MeV and radiation dose power 220 Gr/min on the distance of Im from the target [3] was made for experimental physical researches and activated analysis.  [c.514]

C. Hansch, A. Leo, Exploring QSAR American Chemical Society, Washington (1995). L. B. Kier, L. H. Hall, Molecular Connectivity in Structure-Activity Analysis Research Studies Press, Chichester (1986).  [c.250]

The concentration of Mn in steel can be determined by a neutron activation analysis using the method of external standards. A 1.000-g sample of an unknown steel sample and a 0.950-g sample of a standard steel known to contain 0.463% w/w Mn, are irradiated with neutrons in a nuclear reactor for 10 h. After a 40-min cooling period, the activities for gamma-ray emission were found to be 2542 cpm (counts per minute) for the unknown and 1984 cpm for the standard. What is the %w/w Mn in the unknown steel sample  [c.646]

The concentration of Ni in a new alloy is determined by a neutron activation analysis using the method of external standards. A 0.500-g sample of the alloy and a 1.000-g sample of a standard alloy known to contain 5.93% w/w Ni are irradiated with neutrons in a nuclear reactor. When irradiation is complete, the sample and standard are allowed to cool, and the gamma-ray activities are measured. Given that the activity is 1020 cpm for the sample and 3540 cpm for the standard, determine the %w/w Ni in the alloy.  [c.663]

Activating groups Activation Activation analysis  [c.15]

Trace-element analysis of metals can give indications of the geographic provenance of the material. Both emission spectroscopy (84) and activation analysis (85) have been used for this purpose. Another tool in provenance studies is the measurement of relative abundances of the lead isotopes (86,87). This technique is not restricted to metals, but can be used on any material that contains lead. Finally, for an object cast around a ceramic core, a sample of the core material can be used for thermoluminescence dating.  [c.421]

Elemental chemical analysis provides information regarding the formulation and coloring oxides of glazes and glasses. Energy-dispersive x-ray fluorescence spectrometry is very convenient. However, using this technique the analysis for elements of low atomic numbers is quite difficult, even when vacuum or helium paths are used. The electron-beam microprobe has proven to be an extremely useful tool for this purpose (106). Emission spectroscopy and activation analysis have also been appHed successfully in these studies (101).  [c.422]

Trace-element analysis, using emission spectroscopy (107) and, especially, activation analysis (108) has been appHed in provenance studies on archaeological ceramics with revolutionary results. The attribution of a certain geographic origin for the clay of an object excavated elsewhere has a direct implication on past trade and exchange relationships.  [c.422]

Trace-element analysis provides another approach to these studies, and activation analysis has been appHed successfully in provenance studies of, eg, limestone sculpture (114,115). Marble presents a difficulty because of the large degree of inhomogeneity inherent in this material, which is a consequence of its metamorphic genesis. On the other hand, this same property has been used to advantage in estabUshing whether fragments of broken objects belong together. Multiple sampling along the break planes provides concentration patterns that indicate matching pieces.  [c.423]

Methods for iodine deterrnination in foods using colorimetry (95,96), ion-selective electrodes (94,97), micro acid digestion methods (98), and gas chromatography (99) suffer some limitations such as potential interferences, possibHity of contamination, and loss during analysis. More recendy neutron activation analysis, which is probably the most sensitive analytical technique for determining iodine, has also been used (100—102).  [c.364]

Research and Training Reactors. Research reactors generally fall in one of three categories an experimental reactor to test a concept, a high flux reactor dedicated to basic research, or a reactor used primarily for educational purposes. Reactors at universities or laboratories may be used for purposes such as production of radioisotopes (qv), the study of radiation effects, neutron activation analysis, measurements of reactor properties and behavior, and the teaching of nuclear engineering students. Some of these reactors have been in operation for 30 yr or more without incident. Many university reactors have been shut down for economic reasons. The International Atomic Energy Agency (IAEA) has a catalog of research reactors (76) and includes critical assembhes as well.  [c.224]

When considering pure sihcon, there is much more emphasis on detecting trace impurities in the sihcon than on the detection of sihcon itself. Whereas optical spectroscopy, secondary ion mass spectroscopy (sims), x-ray fluorescence, neutron-activation analysis, and Auger spectroscopy have all been used, indirect electrical measurements generally provide the greater sensitivity required to detect impurities in the parts pet biUion (ppb) range. For example, electrical resistivity measurements allow the detection of <1 ppb of an electrically active impurity, although the impurity itself caimot be identified. There are also various measurements that can be made on diodes, eg, deep-level transient spectroscopy (dlts), that allow the presence of impurities in the ppb range to be inferred.  [c.526]

Gamma-ray spectrometry is a probe of nuclear rather than chemical processes, but its high specificity and sensitivity have appHcations in analysis of materials (286). It is especially suited for activation analysis. Unstable nucHdes produced by nuclear bombardment can be identified by their characteristic gamma-ray decay emissions. An important example is slow neutron capture by nitrogen with subsequent decay of 15 detected from its 1.7—10.8 MeV gamma lines, a signature useful for remote, nondestmctive detection of possible hidden explosives (see Explosives and propellents). Gamma-ray  [c.320]

Numerous methods have been pubUshed for the determination of trace amounts of tellurium (33—42). Instmmental analytical methods (qv) used to determine trace amounts of tellurium include atomic absorption spectrometry, flame, graphite furnace, and hydride generation inductively coupled argon plasma optical emission spectrometry inductively coupled plasma mass spectrometry neutron activation analysis and spectrophotometry (see Mass spectrometry Spectroscopy, optical). Other instmmental methods include polarography, potentiometry, emission spectroscopy, x-ray diffraction, and x-ray fluorescence.  [c.388]

Neutron Activation Analysis. A radiochemical neutron activation analysis technique for deterrnination of 26 elements, including the emitting elements Th and U and Cu, Fe, K, Na, Ni, and Zn, has been developed (44). The radiochemical separation was performed by anion exchange on Dowex 1x8 column from HF and HF—NH F medium, lea ding to selective removal of the matrix-produced radionucHdes Sc, Sc, Sc, and nearly selective isolation of Np and Pa, the indicator radionucHdes of U and Th, respectively. For K, Na, Th, and U, a limit of detection of 30, 0.05, 0.03, and 0.07 ng/g, respectively, was achieved. For the other elements, the detection limits were between 0.002 ng/g for Ir and 45 ng/g for Zr.  [c.244]

Thermal neutron activation analysis has been used for archeological samples, such as amber, coins, ceramics, and glass biological samples and forensic samples (see Forensic chemistry) as weU as human tissues, including bile, blood, bone, teeth, and urine laboratory animals geological samples, such as meteorites and ores and a variety of industrial products (166).  [c.252]

MetaUic impurities in beryUium metal were formerly determined by d-c arc emission spectrography, foUowing dissolution of the sample in sulfuric acid and calcination to the oxide (16) and this technique is stUl used to determine less common trace elements in nuclear-grade beryUium. However, the common metallic impurities are more conveniently and accurately determined by d-c plasma emission spectrometry, foUowing dissolution of the sample in a hydrochloric—nitric—hydrofluoric acid mixture. Thermal neutron activation analysis has been used to complement d-c plasma and d-c arc emission spectrometry in the analysis of nuclear-grade beryUium.  [c.69]

Because of the increasing emphasis on monitoring of environmental cadmium the detemiination of extremely low concentrations of cadmium ion has been developed. Table 2 Hsts the most prevalent analytical techniques and the detection limits. In general, for soluble cadmium species, atomic absorption is the method of choice for detection of very low concentrations. Mobile prompt gamma in vivo activation analysis has been developed for the nondestmctive sampling of cadmium in biological samples (18).  [c.393]

The detection and determination of traces of cobalt is of concern in such diverse areas as soflds, plants, fertilizers (qv), stainless and other steels for nuclear energy equipment (see Steel), high purity fissile materials (U, Th), refractory metals (Ta, Nb, Mo, and W), and semiconductors (qv). Useful techniques are spectrophotometry, polarography, emission spectrography, flame photometry, x-ray fluorescence, activation analysis, tracers, and mass spectrography, chromatography, and ion exchange (19) (see Analytical TffiTHODS Spectroscopy, optical Trace and residue analysis).  [c.371]

Neutron Activation Analysis (NAA) is one of the analytical methods recommended for low level Mo determination in biological materials.  [c.193]

CONTENTS OF ELEMENTS IN DRIED GRAPE RAW, MEASURED BY GAMMA-ACTIVATION ANALYSIS  [c.441]

Neutron Activation Analysis Few samples of interest are naturally radioactive. For many elements, however, radioactivity may be induced by irradiating tbe sample with neutrons in a process called neutron activation analysis (NAA). Tbe 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 13 A1 is placed in a nuclear reactor and irradiated with neutrons, the following nuclear reaction results.  [c.645]

The concentration of Mn in steel can he determined by a neutron activation analysis using the method of external standards. A 1.000-g sample of an unknown steel sample and a 0.950-g sample of a standard steel known to contain 0.463% w/w Mn, are irradiated with neutrons in a nuclear reactor for 10 h. After a 40-min cooling period, the activities for gamma-ray emission were found to be 2542 cpm (counts per minute) for the unknown and 1984 cpm for the standard. What is the %w/w Mn in the unknown steel sample  [c.646]

The concentration of Ni in a new alloy is determined by a neutron activation analysis using the method of external standards. A 0.500-g sample of the alloy and a 1.000-g sample of a standard ahoy known to contain 5.93% w/w Ni are irradiated with neutrons in a nuclear reactor. When irradiation is complete, the sample and standard are allowed to cool, and the gamma-ray activities are measured. Given that the activity is 1020 cpm for the sample and 3540 cpm for the standard, determine the %w/w Ni in the alloy.  [c.663]

M Randic. On characterization of molecular branching. J Am Chem Soc 97 6609-6615, 1975. LB Kier, LH Hall. Molecular Connectivity in Structure-Activity Analysis. Chichester, England Research Studies Press, 1986.  [c.366]

The chemical composition of particulate pollutants is determined in two forms specific elements, or specific compounds or ions. Knowledge of their chemical composition is useful in determining the sources of airborne particles and in understanding the fate of particles in the atmosphere. Elemental analysis yields results in terms of the individual elements present in a sample such as a given quantity of sulfur, S. From elemental analysis techniques we do not obtain direct information about the chemical form of S in a sample such as sulfate (SO/ ) or sulfide. Two nondestructive techniques used for direct elemental analysis of particulate samples are X-ray fluorescence spectroscopy (XRF) and neutron activation analysis (NAA).  [c.205]

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.  [c.645]

W of thermal power, primarily from alpha-particle decay, and this property has been used in space exploration to provide energy for small thermoelectric power units (see Thermoelectric energy conversion). The most noteworthy example of this latter type of appHcation is a radioisotopic thermoelectric generator left on the moon. It produced 73 W of electrical power to operate the scientific experiments of the ApoUo lunar exploration, and was fueled with 2.6 kg of the plutonium isotope in the form of plutonium dioxide, PUO2. Similar generators powered the instmmentation for other ApoUo missions, the Viking Mars lander, and the Pioneer and Voyager probes to Jupiter, Saturn, Uranus, Neptune, and beyond. Americium-241 has a predominant gamma-ray energy of 60 keV and a long half-life of 433 yr for decay by the emission of alpha particles, which makes it particularly useful for a wide range of industrial gaging appHcations, the diagnosis of thyroid disorders, and for smoke detectors. When mixed with berylHum it generates neutrons at the rate of 1.0 x 10 neutrons/(sg) Am. The mixture is designated Am—Be and a large number of such sources are in worldwide daily use in oU-weU logging operations to find how much oil a weU is producing in a given time span. Califomium-252 is an intense neutron source 1 g emits 2.4 X 10 neutrons/s. This isotope is being tested for appHcations in neutron activation analysis, startup sources for nuclear reactors, neutron radiography, portable sources for field use in mineral prospecting and oil-weU logging, and in airport neutron-activation detectors for nitrogenous materials (ie, explosives). Both Pu and Cf are being studied for possible medical appHcations the former as a heat source for use in heart pacemakers and heart pumps and the latter as a neutron source for irradiation of certain tumors for which gamma-ray treatment is relatively ineffective.  [c.225]

From a toxicological and physiological point of view, the determination of micro amounts of selenium is becoming increasingly important. Interest in environmental and human health has promoted development of analytical techniques and methods at the trace and ultratrace levels (see Trace and RESIDUE analysis). The classical, highly selective and sensitive 3,3 -diantinobenzidine method is used widely in the spectrophotometric deterrnination of low levels of selenium. Some instmmental analysis methods used to determine trace amounts of selenium include flame atomic absorption spectrometry, graphite furnace atomic absorption spectrometry, hydride generation atomic absorption spectrometry, inductively coupled argon plasma optical emission spectrometry, inductively coupled plasma mass spectrometry, and neutron activation analysis.  [c.335]

The uranium content of a sample can be determined by fluorimetry, a-spectrometry, neutron activation analysis, x-ray microanalysis with a scanning-transmission electron (sem) microscope, mass spectrometry, and by cathodic stripping voltammetry (8). In most cases, measurements of environmental or biological materials requke preliminary sample preparations such as ashing and dissolution ki acid, followed by either solvent extraction or ion exchange. For uranium isotope analysis, kiductively coupled plasma—mass spectrometry may also be used (81). Another uranium detection technique that has become very popular within the last few years is x-ray absorption near edge stmcture (xanes) spectroscopy. This method can provide information about the oxidation state or local stmcture of uranium ki solution or ki the soHd state. The approach has recently been used to show that U(VI) was reduced to U(IV) by bacteria ki uranium wastes (82), to determine the uranium speciation ki soils from former U.S. DOE uranium processkig faciHties (83,84), and the mode of U(VI) binding to montmorillonite clays (85,86).  [c.323]

Quantitative methods for determining bromide include the Mohr method, using AgNO titrant and potassium chromate indicator the VoUiard method using excess AgNO titrated with potassium thiocyanate and ferric ammonium sulfate indicator Fajans method with AgNO, as titrant, eosin as absorption indicator silver nitrate titrant with the end point deterrnined potentiometricaHy using a silver indicator electrode and a gravimetric method as AgBr. Bromides can be detected in acidic solutions by titrating with mercuric nitrate using sodium nitropmsside indicator. Trace amounts of bromides can be deterrnined quantitatively by the van der Meulen method, which is useful in presence of large amounts of chloride, the bromide is oxidized to bromate and deterrnined iodometricaHy by constant-current and constant-potential coulometry, used for fractions of a milligram up to several grams of bromide by ion chromography, which is useful for detecting bromide in the presence of other ions by polography, useful for microgram quantities (58) by spectrophotometric methods useful for microgram quantities in the presence of chloride (58) and by activation analysis with thermal neutrons which is useful for nanogram quantities.  [c.288]

Chemical analysis of abrasive grain and cmde in the United States is carried out by using a standard analysis scheme approved by the AGA (132) and issued by the ANSI (138). Grain is usually analyzed for siUcon carbide content, free siUcon, free carbon, free siUca, calcium oxide, magnesium oxide, and oxides of iron, titanium, and alurninum. The standard scheme specified by ANSI uses a combination of gravimetric, volumetric, calorimetric, and atomic absorption techniques. Carbon is usually converted by combustion to carbon dioxide, which is then measured by weighing an absorption bulb (138) or by reading the electrical or thermal conductivity (139). A siUcon carbide standard reference material, NBS SRM-112b, is available (140). In Europe and Japan, standard analysis schemes, similar to the ANSI scheme, have been developed by ISO (141) and JSA (142). Instmmental techniques such as x-ray fluorescence, emission spectroscopy, atomic absorption, and neutron activation analysis are used as additional methods of analysis, especially where apphcations require knowledge of a wide range of trace metals.  [c.468]

Instiximental neutron activation analysis (INAA) is considered the most informative and highly sensitive. Being applied, it allows detecting and determination of 30-40 elements with the sensitivity of 10 -10 g/g in one sample. The evident advantage of INAA is the ability to analyze samples of different nature (filters, soils, plants, biological tests, etc.) without any complex schemes of preliminai y prepai ation.  [c.77]

The rare earth elements are eharaeterized by a remarkable similarity of their physieal as well as their ehemieal properties. These similarities make the determination of REE, espeeially at traee levels, a very ehallenging task. But the inereasing interest in their geologieal, industrial and environmental roles, has enhaneed the need for rapid, sensitive and aeeurate methods for their determination. Classieal methods of analysis sueh as gravimetry, eompleximetry, and eolorimetry have all been used for the determination of REE(I-3). Since these methods are typically non-selective and time consuming, they are generally used only for total REE determination. More selective and rapid techniques like neutron activation analysis, atomic spectroscopic techniques, mass spectrometry and X-ray fluorescence spectrometry are currently the methods being used (4-9). Even though all of these methods are capable of determining individual REE, they all require a separation or a pre-concentration step due to matrix and interelement interferences.  [c.205]

Distribution of the contents of isotopes Ti, Ni, Zr, Cs and U in the cores, which was taken from the concrete casing surrounding Chernobyl reactor before accident, was studied. Measurements were carried out by gamma-activation analysis with help of the bremsstrahlung gamma-beam from the high-current electron accelerator. The top energy of the irradiation spectaim was 20.2 MeV, the absorbed doze was 2-10 Gr.  [c.420]

During development of drying circuits for the rests of primary processing grapes, the element content of received raw material components was studied. The initial material was processed in vacuum drying installation at the fixed temperatures in a range 40-60°C. The gamma-activation analysis with help of the high-current electron accelerator was applied to measurements. The content of elements Ca, Mn, Ni, Zn, Rb, Zr, Mo, I and U in skins and seeds of white grapes Aligote and of red grapes Moldova was determined.  [c.441]

Thorinm-232 is the only non-radiogenic thorium isotope of the U/Th decay series. Thorinm-232 enters the ocean by continental weathering and is mostly in the particulate form. Early measurements of Th were by alpha-spectrometry and required large volume samples ca. 1000 T). Not only did this make sample collection difficult, but the signal-to-noise ratio was often low and uncertain. With the development of a neutron activation analysis " and amass spectrometry method " the quality of the data greatly improved, and the required volume for mass spectrometry was reduced to less than a liter. Surface ocean waters typically have elevated concentrations of dissolved and particulate 17,3 7,62  [c.46]


See pages that mention the term Activity analysis : [c.14]    [c.209]    [c.667]    [c.229]    [c.416]    [c.356]    [c.250]    [c.393]    [c.425]    [c.141]    [c.45]   
Applied Process Design for Chemical and Petrochemical Plants, Volume 1 (1999) -- [ c.36 ]