Potassium neutron activation

The need for special facilities for work involving neutron activation analysis and radiochemical measurements has been referred to above in Section 4.3.6. Other safety factors may also influence your choice of method. For example, you may wish to avoid the use of methods which require toxic solvents, such as benzene and certain chlorinated hydrocarbons, or toxic reagents, such as potassium cyanide, if alternative procedures are available. Where Statutory Methods have to be used, there may be no alternative. In such cases, it is essential that staff are fully aware of the hazards involved and are properly supervised. Whatever method is used, the appropriate safety assessment must be carried out before the work is started. Procedures should be in place to ensure that the required safety protocols are followed and that everyone is aware of legislative requirements. 

Potassium bromate is a widely used dough conditioner. However, if it is used in excessive quantities in bread products then appreciable residues (> 1 mg/kg) can remain which is of concern since it is a cancer suspect agent. Its routine analysis is laborious, time-consuming and difficult by HPLC, and Cunningham and Warner (2000) described the development of an instrumental neutron activation method for determination of bromine while HPLC was used to determine bromate in selected samples. 

Flame Photometry, Atomic Absorption, and Neutron Activation. Comparatively few substances amenable to measurement by these techniques are used therapeutically chief among those that are being sodium, potassium, lithium, calcium, magnesium, zinc, copper, and iron, for all of which one or other of the techniques is the method of choice. 

Neutron Activation Spectrometry. Another instrumental technique which has applicability to a wide range of elements is neutron activation analysis. In this method the sample (which could be orange juice without any prior sample treatment) is irradiated with a strong neutron flux. The elements of analytical interest are thus converted to unstable isotopes which decay with characteristic energies and thus measurement of the intensities results in analytical values for the elements of interest. There are some serious drawbacks to this method, however. The matrix can cause severe background effects especially when the sample contains large amounts of an element, like potassium, which is the situation with orange juice. In this event tedious chemical separations must be carried out to achieve adequate selectivity, accuracy... 

Olehy DA, Schmitt RA, Bethard WF. 1966. Neutron activation analysis of magnesium, calcium, strontium, barium, manganese, cobalt, copper, zinc, sodium, and potassium in human erythrocytes and plasma. J Nucl Med 6 917-927. 

The content of acid-soluble iron in paper is determined by TAPPI standard T434 (iron combined in clay and other complex compounds is presumed to be nonreactive). The presence of iron can be shown by the color produced upon wetting the paper briefly with warm 6N hydrochloric acid and then adding a solution of potassium ferrocyanide or thiocyanate localized specks of iron or rust are indicated by the more intense color formation. Complete analysis of paper for metallic elements has been accomplished by chemical procedures, emission spec-trography, scanning electron microscopy/x-ray, and neutron activation. 

Although most of the elements have been determined by XRF (21), some other methods were used. The fluorometric method for selenium uses diaminonaphthalene (32). The colorimetric method for molybdenum uses potassium thiocyanate (33). The uranium analyses were done by delayed neutron activation analysis (34). For the XRF analyses of the oil and water, a blank value implies that there were no x-rays above background for that element. Two elements conspicuously missing from Table IV are cadmium and mercury. Preliminary analyses for these two elements have not yielded reproducible results. Further work is needed before we can make definitive statements about cadmium and mercury. 

Total body neutron activation analysis and whole body counting60 permit the determination of the absolute quantity of certain minerals (including calcium and phosphorus) in the entire body with great accuracy and reproducibility. Since absolute measurements of the total body stores of such elements as calcium and potassium have been normalized for size, sex, age, and body habitus in individual patients, estimates of normal, increased and decreased stores of these elements are possible in a wide... 

Stoltman and Mainfort discussed some of the problems with NAA and most chemical composition studies of pottery. Neutron activation does not identify the minerals in the pottery it identifies only the chemical elements, and those elements that can occur in many different types of parent rock. Pottery is a human artifact whose chemicals derive from at least five sources (1) the clay (2) any added material such as temper (3) the water used to moisten the clay, which may contain such soluble elements as sodium, potassium, calcium, magnesium, or iron (4) any substance stored, cooked, or transported in the pot and (5) diagenesis, the absorption of chemicals from the soil in which the sherds have lain buried for millennia. Because it identifies minerals, ceramic petrography can link the sherd to the bedrock geology from which the temper came NAA, by contrast, cannot distinguish among the five sources that contributed the elements recorded. 

A reasonably complete analysis of the inorganic chemical composition of the aerosol requires much effort and involves, in addition to wet chemical methods, instrumental techniques such as neutron activation analysis, atomic absorption spectroscopy, or proton-induced X-ray emission (PIXE). These latter techniques yield the elemental composition. They furnish no direct information on the chemical compounds involved, although auxiliary data from mineralogy, chemical equilibria, etc. usually leave little doubt about the chemical form in which the elements occur. Thus, sulfur is present predominantly as sulfate, and chlorine and bromine as Cl- and Br-, respectively, whereas sodium potassium, magnesium, and calcium show up as... 

Marinov, V., D. Apostolov, and M. Lazarova Determination of the contents of 20 microelements in tobacco by neutron activation analysis after elimination of sodium-24 and potassium 2 Nucl. Sci. Abstr. 33(1)... 

The analyses of the dust and salt components have been performed by various methods in our laboratory. Neutron activation analysis was used to determine Na, Mg, Al, Ti, V, Mn, Sc, Fe, Co, Sb, Ce, and Eu in dust (28). Fluoride in dust (and the K value in Table III) was done by photon activation analysis (12, 28). The salt portions of the aerosol and rainwater samples were analyzed for Na, K, Cl, and F. Sodium was determined by neutron activation and atomic absorption, potassium by atomic absorption, chlorine by titration, photon activation, and neutron activation, and fluoride by ion-specific electrode and photon activation (12, 28-30). Two analytical methods were used for Na, F, and Cl in the same samples to determine precision and accuracy. 

Radioiodine plays an important role in the diagnosis and treatment of various thyroid disorders. Production methods for various iodine isotopes, namely, and are briefly described in this paper. The chemistry of iodine and radiation effects in aqueous solutions and isotopic exchange reactions are also reviewed. An understanding of the chemistry of iodine is essential in isotope production, and for developing the procedure to prepare the radioactive iodine labeled pharmaceuticals. In radiochemical analysis of iodine, most environmental and biological samples can be accurately analyzed by neutron activation at trace levels. The use of potassium iodide (KI) has become an important remedy to prevent the harmful effects of radioiodine exposure under nuclear accident conditions. The inhibitory effect of KI administration on thyroid radioactive iodine uptake is discussed. 

Phosphorus is analyzed by atomic absorption and ICP emission spectrometry and neutron activation techniques. The total phosphorus contents can be estimated colorimetrically by classical wet methods (American Public Health Association... 1995). Phosphorus is oxidized to orthophosphate by digesting with potassium persulfate. The solution is treated with ammonium molybdate and antimony potassium tartarate in an acid medium to form an antimony-phosphomolybdate complex that is reduced by ascorbic acid to form a deep blue coloration, the intensity of which is proportional to the concentration of phosphorus. The absorbance is measmed at 650 nm by a spectrophotometer. Alternatively, it can be analyzed colorimetrically by an autoanalyzer (Technicon model). 

HCI = hydrochloric acid HNO3 = nitric acid ICP = inductively coupled argon plasma spectroscopy KNO3 = potassium nitrite MIBK = methyl isobutyl ketone NAA = neutron activation analysis NH 4HCO3-DTPA = ammonium bicarbonate-diethyl enetriaminepentaacetic acid NR = not reported... 

The most common method of analytical determination of rubidium is atomic absorption spectroscopy (AAS) or neutron activation analysis (NAA). Chemical methods of analysis for the determination of rubidium are difficult because of the tedious procedures required to effect the separation from the other alkali metals. The beneficial effects of the addition of other alkali metals, particularly potassium, sodium, and cesium, added to interfere with the ionization of rubidium is detailed by many authors [39,53-55]. Recent evaluation of the benefits of these ions in the determination of rubidium in human erythrocytes has concluded that erythrocytes should be diluted 1 50 with potassium to give a final potassium concentration of 10000 ppm. Under these conditions, the sensitivity of absorbance was increased about threefold and rubidium concentrations could be determined in the range 0-60 ppm [56]. 

Helmke, P. A. 1996. Neutron activation analysis. In Methods of Soil Analysis. Part 3. Chemical Methods, ed. D. L. Sparks, 141-160. Soil Science Society of America Book Series 5. Madison, WI American Society of Agronomy-Soil Science Society of America. Helmke, P. A., and D. L. Sparks. 1996. Lithium, sodium, potassium, rubidium and cesium. In Methods of Soil Analysis. Part 3. Chemical Methods, ed. D. L. Sparks, 551-574. Sou Science Society of America Book Series 5. Madison, WI American Society of Agronomy-SoU Science Society of America. 

One of the more successful targets, however, is potassium chromate (40), when an enrichment of chromium-51 with respect to natural chromium of several thousand is obtained, giving specific activities usually better than 10 curies of 51Cr per gm Cr at neutron fluxes of the order of 1012 n/cm2/sec from an irradiation of one week. 

Merrihue C. and Turner G. (1966). Potassium-argon dating by activation with fast neutrons. J. Geophys. Res., 71 2852-2857. 

The Ge(Li) gamma-ray spectrum of thermal neutron irradiated cigarette tobacco as obtained in our laboratory is shown in Fig. 8. In this case a 50 day decay period has eliminated the major portion of interferences from sodium, potassium and phosphorus activities. Assignments of photopeaks in this figure may be regarded as tentative, since half-lives of the individual peaks were not followed. As many as fifteen elements have been determined in tobacco products and biological standard kale... 

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