Yield of Tc in Liquid-Liquid Extraction

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In this exercise you will learn how to use a radionuclide to measure a feature of an element, in addition to how radionuclides can be used as a tracer to study a chemical reaction.

The exercise will show how Tc can be extracted from an aquatic phase by using liquid-liquid extraction. It will illustrate how easy it is to follow a radioactive element during a reaction. Therefore tracers are used in a lot of different tests in several branches of industry and academics.

To a 15 mL test tube add 2.5 mL 0.1 M HNO3 / 0.05 M KBrO3 solution. Then add 0.5 mL of 99mTc solution. Then add 3.0 mL 0.05 M trioctylamin dissolved in toluene. Shake the solution vigorously for one minute. Transfer 2 mL of each phase to a glass vial. Be precise so that you don't mix the phases in the vial. It is often better to transfer 2 mL of the upper phase, then remove the rest of it. Then transfer 2 mL of the bottom phase.

The amount 99mTc in the two phases is decided by quantitative analysis of the γ spectrum. Measure the spectrums and write down the following:
Counts in organic phase, Norg (“Net Area”): …..........................
Counting time for organic phase, torg(“Live Time”):....................sec
Counting speed for organic phase Rorg(Norg/torg):....................cps


Counts in water phase, Naq (“Net Area”):.........................
Counting time for water phase, taq (“Live time”):..................sec
Counting speed for water phase Raq(Naq/taq):....................cps
Distribution, D=Rorg/Raq:...................
Extraction yield, E=Rorg/(Rorg+Raq)[math]\cdot[/math]100............... %