Yield tracers

Zhu HM, Tang XZ. 1989. Determination of lead in environmental soil using lead-238 as a yield tracer. 

Analysis of technetium is usually made after chemical separation of the element and it requires a chemical yield tracer (99mTc or 95mTc). These sometimes make... 

Koide et al. [537] have described a graphite furnace atomic absorption method for the determination of rhenium at picomolar levels in seawater and parts-per-billion levels in marine sediments, based upon the isolation of heptavalent rhenium species upon anion exchange resins. All steps are followed with 186-rhenium as a yield tracer. A crucial part of the procedure is the separation of rhenium from molybdenum, which significantly interferes with the graphite furnace detection when the Mo Re ratio is 2 or greater. The separation is accomplished through an extraction of tetraphenylarsonium perrhenate into chloroform, in which the molybdenum remains in the aqueous phase. 

Nuclide Yield Tracer Chemical Form Activity Counted... 

Various workers [32-34] have discussed mass spectrometric and other methods for the determination of plutonium in soils. Plutonium in soils has been quantified using 238plutonium as a yield tracer. Hollenbach et al. [36] used flow injection preconcentration for the determination of 230Th, 234 U, 239Pu and 240Pu in soils. Detection limits were improved by a factor of about 20, and greater freedom from interference was observed with the flow injection system compared to direct aspiration. 

Figure 13.3 Alpha spectrum of oxidised and reduced plutonium species as separated by the neodymium fluoride technique (oxidised yield tracer 236Pu, reduced yield tracer 242Pu).

Harvey, B.R. and Lovett, M.B. (1984) The use of yield tracers for the determination of alpha-emitting actinides in the marine environments. Nucl. Instr. Meth. Phys. Res., 223, 224—234. 

Plutonium-242 and Americium-243 Pu-242 and Am-243 are produced in fuel by multiple nuclear reactions. They therefore appear in items contaminated by fuel. They were found to exceed the GQ limit in HNA and HPA MCI and HPA SPF waste (high uncertainty). In addition in IX resins at HPA and HNA, Am-243 was above the GQ. Neither of these radionuclides are currently analysed in Magnox wastes because they are used as yield tracers in other analyses. To measure these two radionuclides, it is possible to simply repeat the current analyses for Pu and Am with and without tracers. No development work should be required. It has been possible to use these isotopes as tracers because the amount present (in terms of activity) is very low. FISPIN predicts the following radioisotope ratios in fresh waste Am-241 to Am-234 of 111 to 1 and Pu-239/-240 to Pu-242 of 2,500 to 1. At these activity levels, it may be more accurate to estimate the activities rather than measure them. 

Radiochemical yield tracers, Po or Po, are almost universally employed to allow correction for losses. The former has historically been the most widely used tracer, however Po has advantages due to greater energy separation of the peaks, and a longer half-life resulting in a greater effective lifetime of the tracer solution. 

Nitrile synthesis. Sodium salts of carboxylic acids when heated in a sealed tube with cyanogen chloride at 200-300° are converted into the corresponding nitriles, often in high yield. Tracer studies with cyanogen bromide have shown that the carbon dioxide liberated is derived from the cyanogen halide and that the bond... 

Samples of 17.51 in volume were collected, stabilized with nitric acid and shipped to the laboratory for further processing. The samples were volumetrically measured, acidified to a pH of > 1.0, had an Fe carrier added and were spiked with a known quantity of an artificial isotope useful as a yield tracer. 

J.P. Hunt, H. Taube (1952). The photochemical decomposition of hydrogen peroxide. Quantum yields, tracer and fractionation effects. Nature, 74, 5999-6002. 

An improved isotope dilution mass spectrometrie technique was developed for the analysis of in environmental samples, is isolated from the sample, after spiking with Tc as a yield tracer, by ion-exchange chromatography and solvent extraction. Technetium is then concentrated onto a pair of anion exchange beads of 0.3 mm in diameter. Determination of 10 g of technetium was achieved through the enhanced ionization efficiency afforded by the resin bead source [50]. Spark source mass spectrometry was... 

Carriers are added to radionuchde solutions, as discussed in Section 4.7, to perform precipitation separations, avoid radiocolloidal behavior, and to eliminate the need for quantitative recovery by allowing the analyst to calculate the fractional chemical recovery ( yield ). A radioactive tracer (see Section 4.7.3) can be added to the sample in addition to or instead of the carrier to measure yield. Tracer addition may make yield determination easier than carrier addition, or may be necessary if no carrier is available. 

If no Fe is in the sample, as confirmed by sample analyses, it can be added as yield tracer for Fe analysis. After ion-exchange purification, the elutriant is measured by LS counting Fe and Fe in different energy regions. Cross-talk from the Fe beta particles in the Fe Auger electron region must be corrected, as well as color quenching from chemicals. 

Recovery measurements are often performed with the addition of radiotracers, which are most likely analyzed together with the analyte in the measurement source. Since the tracers should not be produced in the sample during irradiation, cyclotron-produced tracers are preferred in NAA, e.g., Co analysis by NAA in the presence of cyclotron-produced Co yield tracer. High accuracy in the analysis can only be assured if recovery for each analyte in each sample is determined. 

Radionuclides are usually extracted from filtrates of discrete samples (from the Rosette sampler, Gerard bottles or from the ship s seawater supply) by coprecipitation as Fe(OH)3, Mg(OH)2, Mn02, BaS04, PbS04 or Co-APDC. If quantitative recovery cannot be guaranteed, yield tracers are used. The sample volume has to be known accurately. Large volumes can be metered with a water meter (approximately 1 % error). Samples of approximately 25 L can conveniently be weighed on board with a balance (precision approximately 50 g). 

Pb yield tracer (20 g/L Pb) Lead chemicals and standard materials contain Pb. For sufficiently low background levels, carry out a digestion of a certified lead ore such as the sulphide ore galena (Fleer, personal communication). 

Tare the balance with an empty canister. Weigh a 20 L filtrate sample. To 20 kg of filtered seawater are added 20 mL of concentrated HNO3, appropriate yield tracers and 5mL of FeCls solution (50 mg/mL Fe " ). 

Precipitate Fe(OH)3, using 1 mL of Th spike (16dpm/mL) as the yield tracer (Section 13.7.3). Take up the precipitate in 9mol/L HO. Add some concentrated HO to make up for reaction with 5 nunol of Fe(OH)3. The solution should be 9 mol/L in HO and have a volume of approximately 30 mL. Allow some time for complete dissolution. 

Rad AG1-X8) and added to a small anion-exchange column. The Ra was removed from the column using 0.005 mol/L EDTA-0.1 mol/L ammonium acetate solution at pH = 8 while Pb remained on the column. The Ra was then passed through a cation-exchange column (Bio-Rad AG50W-X8) in 3 mol/L HNO3 to remove residual Th. The purified Ra was electro-deposited on a stainless-steel planchet and after 15-20 min, placed in an alpha spectrometer. The initial count was used to measure Ac, the daughter of Ra, to determine the recovery of the Ra yield tracer. Additional coimts were required to determine the activities of the other Ra isotopes. 

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