Preparation of Counting Samples

Lab Exercise - Preparation of Counting Samples

Developed By


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

Explanation and Exercise  Guide


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.

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.

Questions for the Students

Here there should be relevant questions regarding the theory of the exercise which should be possible to answer after the exercises have been performed. The questions should be molded into the report that the students write after the exercises in such a way that it feels natural.


How to do calculations or other important aspects for the theory that is not directly related to exercise.

Safety Aspects

See above


See in procedure