Measurement+of+55Fe+by+Liquid-Scintillation+Counting

Back to Main Add 9.5 mL of scintillation cocktail **Optiphase ’Hisafe’3** (LKB, Wallac). Shake well. Measure after ½ hour with a liquid scintillation counter.

To be able to calculate 55 Fe radioactivity, counting efficiency need to be determined **(efficiency calibration).** Counting efficiency is determined from a 55 Fe standard series using **Fluorescein** (C 20 H 12 O 5 ) as a quenching agent.

A quenching standard series Add reagents into plastic scintillation vials as follows:
 * || 55 Fe (X Bq/ml) || MQ-H2O || HF || **Fluorescein** || Scintillation cocktail ||
 * 1 || 0.5 ml || 2 ml || 1 drop || 0 ml || 9.5 ml ||
 * 2 || 0.5 ml || 1.9 ml || 1 drop || 0.1 ml || 9.5 ml ||
 * 3 || 0.5 ml || 1.8 ml || 1 drop || 0.2 ml || 9.5 ml ||
 * 4 || 0.5 ml || 1.6 ml || 1 drop || 0.4 ml || 9.5 ml ||
 * 5 || 0.5 ml || 1.0 ml || 1 drop || 1.0 ml || 9.5 ml ||

Shake well. After ½ hour measure the samples in a liquid scintillation counter.

Draw a quenching standard quenching curve. Determine the counting efficiency for 55 Fe from the curve.