Difference between revisions of "Laboratory Exercise - Safe Working Practise in the Radionuclide Laboratory and Preparation of Counting Samples"

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(Theory)
(Experimental procedure)
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=== Experimental procedure  ===
 
=== Experimental procedure  ===
  
We are going to use a modern liquid-scintillation counter (LSC) with three PM-tubes. This enables it to use the Triple-to-Doubble-Coincidence-Ratio (TDCR) parameter for quench correction. We will both use the traditional channel-ratio method and the TDCR method to investigate quenching in LSC samples. For this we will use <sup>14</sup>C samples quenched with CCl.  
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The objective of the exercise is to learn safe handling of radionuclide-containing solutions and to prepare counting samples for measurement in the following radiochemistry laboratory course.  
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Perform the exercise on a tray, and always keep absorbent cellulose available. Wear gloves when pipetting. Use an adjustable automatic pipette (Finnpipette, Biohit) and change tips between different solutions. Under no circumstances contaminate the pipette by turning it so that the tip is uppermost.
  
'''Part 1: Initial tests'''
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# Preparation of 32P samples
  
*Measure <sup>3</sup>T and <sup>14</sup>C standards to get familiar with the machine (HIDEX 300) (2 min each).
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## The activity concentration of the 32P stock solution used in this exercise is XXX kBq/mL. It also contains carrier phosphate of concentration ~10-4 M.
*Measure an empty vial with 10-mL scintillator (and nothing else) inside (10 min or more).  
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## Take a tray for your group and cut some protective paper (shiny side up) to cover its upper, inner surface. Draw a grid on the paper, and mark the columns A–D and the rows 1–5.
*Measure an empty vial without scintillator solution (10 min or more).
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## Take five 20 mL plastic vials and mark them 1, 2,.., 5. To each vial, pipette 4 mL gelatin solution (0.2% gelatine, 10-4 M phosphate, 0.03% sodium dodecyl sulphate and 2∙10-2 M sodium hydroxide). Pipette 1, 2,.., 5 mL 32P stock solution into vials 1, 2,.., 5, respectively. Fill each vial with water so that their volumes are all 10 mL, close their caps and shake them gently ten times (vigorous shaking will cause undesirable foaming).  
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## Make four parallel counting samples for each 32P dilution: Take twenty aluminium discs and mark their reverse sides 1A, 1B,.., 5D. Place the discs in their designated positions on the tray. Pipette 0.2 mL solution from vial 1 to each disc in row 1, and proceed similarly for rows 2–5.
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## Use a surface contamination meter to make a few control measurements. The instructor will direct you in correct procedure.
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## Leave the samples in a fume cupboard to dry overnight. The samples will be used in Basic radiochemistry laboratory exercise course.
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7) Dispose of your 32P dilutions accordingly. The dilutions and first washings of the vials go into the waste container. Rinse the vials many times with tap water and then dispose of them in the normal waste.
  
'''Part 2: Quench Correction'''
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2. Detection of surface contamination
  
*Prepare 10 20-mL vials with 10-mL LSC cocktail in each
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The teacher has evaporated one or several drops of 134Cs, emitting both  and  radiation, solution on a table having 25 blocks. The has coordinates 1-5 on the other edge and A-E  on the other. The blocks containing the "contamination" should be detected with a PCM 5/1 detector. Turn on the detector, and switch Electra to "" mode and write down the high voltage. Test the detector with a calibration source given by the teacher.  
*Add a suitable amount of <sup>14</sup>C activity to obtain at least 50,000 counts in a 2- or 3-min measurement.  
 
*Measure the 10 samples to check for consistency - they should all give the same result.  
 
*Quench 9 of the samples with suitable amounts of CCl (10-200 uL) to cover the whole quenching range.  
 
*The measurement results will contain Doubble-Coincicdence and Triple-Coincidence spectra. There is also predefined regions of interest (ROI) which can be used to calculate the traditional quenching parameter (channel ratio) directly (instead of integrating different parts of the spectra).
 
  
'''Part 3:&nbsp;Mixture of <sup>3</sup>H and <sup>14</sup>C'''
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3. Filling in the exercise form
  
*Prepare one sample with only <sup>3</sup>H and one sample with about equal amounts of <sup>3</sup>H and <sup>14</sup>C.
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Fill in the exercise report form provided, and submit it within two week after completion of the exercise.
*Count the samples (count until you have at least 50,000 counts in each).
 
*Compare the 3H spectrum to the 14C spectrum from Part 1 (or 2). How can such mixtures be analysed to get the desintegration rate of the individual nuclei?
 
*Get an unknown sample from your supervisor and count it. The <sup>3</sup>H and <sup>14</sup>C content of this sample should be determined.
 
 
 
'''Part 4:&nbsp;Other nuclei'''
 
 
 
*A solution of H3PO4 has been n-irradiated for several days.
 
*Prepare two samples:&nbsp;Extract 200 uL from the H3PO4 solution and add it to A) a counting vial with 10 mL&nbsp;scintillation cocktail and B) a counting vial with 10 mL&nbsp;deionised water.
 
*Count both solutions with suitable setups (your supervisor will guide you).
 
  
 
=== Equipment  ===
 
=== Equipment  ===

Revision as of 19:49, 21 November 2012

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Learning Goals

After having performed this exercise you should:

  • Understand the basics of practical radiation protection.
  • Know how to prepare typical counting samples for radiation measurements.

Theory

Experimental procedure

The objective of the exercise is to learn safe handling of radionuclide-containing solutions and to prepare counting samples for measurement in the following radiochemistry laboratory course. Perform the exercise on a tray, and always keep absorbent cellulose available. Wear gloves when pipetting. Use an adjustable automatic pipette (Finnpipette, Biohit) and change tips between different solutions. Under no circumstances contaminate the pipette by turning it so that the tip is uppermost.

  1. Preparation of 32P samples
    1. The activity concentration of the 32P stock solution used in this exercise is XXX kBq/mL. It also contains carrier phosphate of concentration ~10-4 M.
    2. Take a tray for your group and cut some protective paper (shiny side up) to cover its upper, inner surface. Draw a grid on the paper, and mark the columns A–D and the rows 1–5.
    3. Take five 20 mL plastic vials and mark them 1, 2,.., 5. To each vial, pipette 4 mL gelatin solution (0.2% gelatine, 10-4 M phosphate, 0.03% sodium dodecyl sulphate and 2∙10-2 M sodium hydroxide). Pipette 1, 2,.., 5 mL 32P stock solution into vials 1, 2,.., 5, respectively. Fill each vial with water so that their volumes are all 10 mL, close their caps and shake them gently ten times (vigorous shaking will cause undesirable foaming).
    4. Make four parallel counting samples for each 32P dilution: Take twenty aluminium discs and mark their reverse sides 1A, 1B,.., 5D. Place the discs in their designated positions on the tray. Pipette 0.2 mL solution from vial 1 to each disc in row 1, and proceed similarly for rows 2–5.
    5. Use a surface contamination meter to make a few control measurements. The instructor will direct you in correct procedure.
    6. Leave the samples in a fume cupboard to dry overnight. The samples will be used in Basic radiochemistry laboratory exercise course.

7) Dispose of your 32P dilutions accordingly. The dilutions and first washings of the vials go into the waste container. Rinse the vials many times with tap water and then dispose of them in the normal waste.

2. Detection of surface contamination

The teacher has evaporated one or several drops of 134Cs, emitting both  and  radiation, solution on a table having 25 blocks. The has coordinates 1-5 on the other edge and A-E on the other. The blocks containing the "contamination" should be detected with a PCM 5/1 detector. Turn on the detector, and switch Electra to "" mode and write down the high voltage. Test the detector with a calibration source given by the teacher.

3. Filling in the exercise form

Fill in the exercise report form provided, and submit it within two week after completion of the exercise.

Equipment

  • HIDEX 300 Automatic TDCR Liquid Scintillation Counter

Safety Aspects