Detection radionuclides

Samples Method Radionuclides Detection limits/lsotope ratios measured References... 

Samples Equipment Radionuclides Detection limits References... 

Table V presents the leaching data for Melt Glass 3 only. Glasses 1 and 2 were omitted from this interim report since they were both older than 3 and provided lower sensitivity for radionuclide detection. The data in Table V were calculated using the following equation (12)...

Radionuclide Analyses of Foods. A few food items purchased at a local grocery store were similarly prepared and counted. The results are tabulated in Table I. In all cases the only radionuclides detected were 137Cs and 40K. The photopeaks were easily discernible the lowest level was 12.7 pCi, 137Cs for a 228-gram sample of shrimp. 

Page, J. S., and Sweedler, J. V. (2002). Sample depletion of the matrix-assisted laser desorption process monitored using radionuclide detection. Anal. Chem. 74 6200-6204. 

Smith, M. R., Farmer, O. T., Reeves, J. H., and Koppenaal, D. W., Radionuclide detection by ion-chromatography and on-line ICP/MS and beta detection Fission product rare earth element measurements, J. Radianal. Nucl. Chem., 194, 7-13, 1995. 

A sample from a suspected nuclear incident is processed by gamma-ray spectral analysis. The sample does not contain any "Mo, or at least none is observed. Also, the sample contains large amounts of 60Co and 137Cs but no other radionuclides detectable by gamma-ray emission. What do you conclude ... 

Besides radionuclides (detected on the basis of beta and gamma radiation), labels detected by the measurement of magnetic resonance have been proposed (spin labels - spin immunoanalysis, abr. SIA). Other labels are fluorescent dyes already... 

Smith, M.R., Wyse, E.J. and Koppenaal, D.W., Radionuclide detection by inductively coupled plasma mass spectrometry a comparison of atomic and radiation detection methods. J. Radioanal. Nucl. Chem., 160(1992) 341. 

When a liquid volume of several liters is needed to achieve a specified sensitivity for radionuclide detection, the volume usually is reduced for ease of analysis. Evaporation is a simple approach. A faster process— and one that is necessary for samples of seawater or other high-salt-content solution—is precipitation of the radionuclides of interest from the large sample volume with a carrier in bulky insoluble forms such as phosphate, hydroxide, or carbonate. The precipitate bearing the radionuclides of interest is separated by decanting most of the solution and filtering the rest, and is then dissolved for further radionuclide purification. 

Detector quality control records are reviewed to assure that control samples and the radiation background have been measured recently and that the detectors in use are within control limits (Section 11.2.10). Brief control source and background measurements are performed before the screening process begins to assure that detectors continue to operate appropriately and have not been contaminated recently. The detection limit in terms of activity per sample is calculated for all radionuclides of interest to determine whether a null result will meet radionuclide detection requirements for the submitted samples. 

This chapter provides an overview of mass spectrometer function and operation. It describes specific instrument types with demonstrated or potential application for measuring radionuclides and surveys the application of these instruments to radionuclide detection. Finally, it discusses the circumstances under which use of mass spectrometers is advantageous, the type of mass spectrometer used for each purpose, and the conditions of sample preparation, introduction and analysis. Its perspective is from a national laboratory active in environmental and non-proliferation monitoring. It emphasizes isotope ratio measurements, but mass spectrometric measurements also provide isotope mass information. Several recent books describe elemental and isotope ratio mass spectrometry in far greater detail than is presented here (Barshick et al., 2000 De Laeter, 2001 Montaser, 1998 Nelms, 2005 Platzner, 1997 Tuniz et al., 1998). High-resolution mass spectrometry forms the basis of the mass scale used for elemental and isotopic masses (Coplen, 2001), but this application of MS falls outside the scope of this chapter. 

In the post-column detection configuration, detection is carried out at a location remote to the outlet of the capillary. For example, in radionuclide detection, the capillary eluent is spotted onto a membrane or collected as fractions, and subsequently exposed to a scintillator for detection Postcolumn detection allows for the separation and detection to be independently optimized. In the case of radionuclide detection, the detector integration time can be maximized without a corresponding loss in resolution (see Section 9.2.2). 

In radionuclide detection, the presence of a radiolabeled analyte is detected by the response of a secondary substance to the radioactive decay of the radiolabel. The secondary substance is referred to as a scintillator, and it responds to collision with a radioactive particle by the emission of photons. Since it is this emission of photons that is actually measured in radionuclide detection, it is appropriate that this method of detection be included in a chapter covering light-based detection methods. Radionuclide detection is both highly sensitive and selective. The high sensitivity of this technique is due to the ease of detection of the energetic decay events, in conjunction with a very low natural background. The high selectivity of this technique results from the fact that only the radiolabeled sample yields a detectable response. As a consequence, it is possible, for example, to inject a... 

The sensitivity and detection limits for radionuclide detection depend in large part on the particular radioactive nuclei being used. More specifically, the isotope s rate of decay and particle energy determine the lowest attainable detection limit. In addition, the sensitivity is dependent on the observation time of the isotope and the fraction of events detected, which can be expressed as follows ... 

Both on-column and post-column detection schemes have been developed for radionuclide detection for CE. The most common type used is an on-column configuration, which yields detection limits in the 10 M range for isotopes such as P. Isotachophoretic separations of C were among the first examples of online capillary radionuclide detection, performed by Kaniansky et al. The associated instmment uses 300-p,m ID fluorinated ethylene-propylene copolymer capillary tubing, and the separation eluent flows directly into a plastic scintillator cell between two PMTs. The scintillation events are detected coincidentally between the two PMTs, such that only if both PMTs receive an input within a short time will they register the count as signal. This kind of coincidence detection ensures that nonscintillation photons that come from outside the detection cell and only hit one PMT are not counted. This system exhibits a detection limit of 16 Bq for analytes, with a detector efficiency of 13-15%. 

FIG U RE 9.7 Post-column radionuclide detection system for CE. The spots can be analyzed by other deteetion modes, such as mass spectrometry, to gain additional information. (Reprinted from Page, J. S., et al.. Anal. Chem., 74, 497, 2002. With permission.)... 

The chart is helpful when tracking down unknown radionuclides detected in a measurement to know what type of nuclear reaction may have been responsible for the production of the activity. In most cases, this will be a thermal neutron reaction resulting in activation by (n, 7), or if the target material is fissile, a fission reaction (n, f). 

Concentrations of Gamma-Emitting Radionuclides Detected in Deer Mice Collected Around the 116-N-l Trench, 1981 (pCi/g-wet/wt). T5-33... 

Table 5-24. Radionuclides Detected in Rabbits Collected Around the 116-N-Facility, 1981 Concentrations in pCi/g (wet weight). (2 Sheets)...

Radionuclides Detected in Rabbit Feces Collected Around the 1301 N Facility in pCi/g (dry weight). 1981 Concentration ... 

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