Tritium counting

The most frequently used combination of radioisotopes in double labeling experiments is tritium and 14C. Ideally the ratio of the activities in the corresponding channels (Fig. 7.16) should to be high enough to insure the carbon counts in the tritium channel are negligible compared to tritium counts. Usually this is not achieved and a correction must be applied. 

A tritium plateau determination is shown in Figure 6, for the II detector. Using the TMC and ORTEC electronics, the observed results are slightly different than from the Sharp electronics, owing to different logic. The usable range of the tritium counting plateau is ca. 400 volts at 400 cm. Hg pressure. 

Tritium count/Hydrogen content) of coal extract (Tritium count/Hydrogen content) of phenanthrene... 

In this experiment, tritiated water is purified by simple distillation, and the tritium beta particles in the condensate are measured with a liquid scintillation (LS) counter. Such distillation also can collect tritiated water samples from solids. Tritium in other forms must be processed before it can be counted like tritium in water for example, tritiated hydrogen gas and tritiated organic substances can be oxidized to form water. Additional separations may be needed if the liquid or solid sample contains radioactive gases or volatile substances other than tritium that may be collected with the distilled tritiated water. Such radioactive impurities can be identified in the data output from the LS counter of an energy spectrum that differs from that of pure tritium, or of counts in energy regions where tritium counts are not found. 

Although our initial concerns about possible interferences due to chemiluminescence and quenching effects have been somewhat mitigated by recent disclosures of Blank and Kidwell s tritium counting procedures, an entirely different problem exists concerning their isotopic method, one that in our opinion casts serious doubt upon the general suitability of their approach for doing hair contamination/decontamination studies. 

J. Sharpe and V. A. Stanley, Int. At. Energy Agency, 1 211 (1952). Photomultipliers for Tritium Counting, in Tritium in the Physical and Biological Sciences (Proceedings of a Symposium on the Detection and Use of Tritium in the Physical and Biological Sciences). 

Lieberman, R., Moghissi, A.A., Low-level counting and liquid scintillation—II Applications of emulsions in tritium counting. Int. J. Appl. Radiat. Isot., 21 (1970) 319-327. 

HX has been measured by all combinations of H-H, H-D, and H-T approaches. At lowest resolution, HX can be measured at a whole molecule level using radioisotopic tritium counting and by various spectroscopic methods that are sensitive... 

FIGURE 4. Comparison of tritium counting efficiency versus sample load for new (a, b) and classical (c, d) scintillators. 

In order to evaluate which effect the formation of reversed micelles might have on the counting efficiency of tritium beta particles,in a second series of experiments the (tritium) counting efficiencies of toluene solutions containing PPO - POPOP fluors and 0 or 2 % water, respectively, were... 

These transitions observed by this method are also reflected in the tritium counting efficiency which decreases strongly at higher water concentrations and indicate a preferential trapping of the weaker beta particles in the water environments. Consistent with these assumptions, this effect is less pronounced when beta particles are more energetic and are therefore capable of sampling the whole solution. 

Each of the count rates, A,B,C, and D in the preceding equation has an associated error, 6A,6b,6C and 6d. From the errors, the combined error for the tritium count rate, 6e, is calculated as ... 

The count rates used in Eqs. (1 - 6) are the weighted averages of the count rates obtained by measuring 15 vials for each sample for multiple 20 minute count periods. This calculation, the efficiency calibration, and the relatively complicated evaluation of the tritium count rate and its error using Eqs. (5 - 5) justifies the development of a computer algorithm. 

Figure 3 is a detailed flow chart of the algorithm. The only problems in implementing the algorithm are those related to intermediate storage of the variables. Eq. (5) the expansion for e, the tritium count rate has a rather complex form. 

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