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Part 1 - The Volume Effect

1. An aqueous solution of 32P solution has been provided. Place 1 cm3 of this solution in a polythene 20 ml scintillation vial and count in the scintillation counter in the 3H channel, which should be set so that the full tritium range is displayed in channel one and a third of the tritium range in channel two (protocol 28)
2. Set up a further 14 scintillation vials with 1 cm3 of 32P soln. Add 1 cm3 of H2O to one vial, 2 cm3 to the next, 3 cm3 to the next, and so on until 14 cm3 has been added to the final vial
3. Count them all on the scintillation counter using protocol 28
4. Plot a graph showing the counting efficiency as a percentage of the maximum activity
5. Deduce the optimum counting volume.

Part 2 - Colour Quenching

1. Put 1 cm3 of the 32P solution into a scintillation vial and make up to 12 cm3 with distilled water
2. Count the sample using protocol 28
3. Add successively 0.1, 0.1, 0.2, 0.4, 0.4, 0.6 and 0.6 cm3 of the 0.25% v/v of methyl violet in alcohol solution provided to the vial of 32P
4. Record the counts for after each addition in the both of the channels
5. Work out the channel ratio and plot a graph showing the activity of the solution as a percentage of the unquenched sample against the channel’ ratio
6. Repeat the expt using the 0.25% v/v of methyl orange in alcohol solution provided
7. The quench curves should be identical until a very high degree of quenching is obtained, after which some variation in the two curves may be obtained