Extraction+and+Measurement+of+99mTc+from+a+Isotope+Generator

Back to Main The supervisor will extract some 99m Tc solute and transfer 20 mL of a solute that contains 0.1 M HNO 3 and 0.05 M KBrO 3 for each group. The amount of 99m Tc received is too small to impose any health risk, but still use extreme caution.

Always transport radioactive solutions in a container where the inside is covered with absorbing paper, ideally a lid should be used as well. Remember to keep contaminated equipment separated from the all the other equipment. //Work and storage of radioactive solutions shall always be done with absorbing paper beneath. Use gloves, glasses and lab-coat.// Put your solution of 99m Tc in a steady frame inside of your fume hood.

=Yield of Tc in Liquid-liquid Extraction= 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 HNO 3 / 0.05 M KBrO 3 solution. Then add 0.5 mL of 99m Tc 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, N org (“Net Area”): …..........................

Counting time for organic phase, t org (“Live Time”):....................sec

Counting speed for organic phase R org (N org /t org ):....................cps

Counts in water phase, N aq (“Net Area”):.........................

Counting time for water phase, t aq (“Live time”):..................sec

Counting speed for water phase R aq (N aq /t aq ):....................cps

Distribution, D=R org /R aq :...................

Extraction yield, E=R org /(R org +R aq )•100............... %

=Measurement of 99m Tc 𝛾 -spectrum= This exercise will teach you to use a NaI-detector to take a spectrum of the γ from 99m Tc. You learn to analyze the spectrum to determine the amount of 99m Tc in the sample. Remember gloves, glasses and lab-coat. //If there is some spillage on the gloves control them and immediately change them//. Contaminated gloves goes in the designated waste bucket for solid active waste. Extract 0.5 mL of 99m Tc from the solution you received from the supervisor with an automatic pipette and transfer it to a 20 mL glass vial and put on the lid. Throw away the pipette tip in the designated waste bucket for solid radioactive waste. Control the outside of the glass vial by drying it with some paper then measure the paper for contamination with the hand held detector. When you are certain that the glass vial is not contaminated on the outside you can take it to the counting room.

Set the counter to 180 seconds to measure the background ( don't put your glass vial in front of the detector) print out the background spectrum. Delete the background spectrum and put your sample of 99m Tc in front of the counter. Take a new spectrum of your sample set it to count for 180 seconds, when it is done print out the spectrum. The Tc top is marked with red, if it not marked the tops should be around 322 keV. Press the left mouse button on the top and you will receive data on it. Number of counts, N, in the top (“Net Area”): …............................. Total number of counts, N tot, in the marked area(“gross area”):................. live time : …........................sec count rate, R=N/t: …..................sec energy of γ -gamma top ................ keV will the background give false counts in the 99m Tc-top? Explain why/why not with a sketch: