A method for measuring specific activities of14C-labelled compounds by gas chromatography-mass spectrometry-computer system (GC-MS-CPU) was developed. This method was proved to provide practically precise and accurate specific activities of various14C-labelled compounds with such merits as requirement of small amount of samples, being applicable to volatile compounds, and convenience. The C. V. percent obtained for tested compounds was within 3.9 and the reliable sensitivity should be over 37 MBq/mM (1 mCi/mM) . This method was also useful for obtaining information on the labelling pattern and the synthetic procedures applied.
A simple and rapid method has been improved for determination of low specific activity of55Fe with a liquid scintillation counter. High counting efficiency was obtained for a sample containing up to 150 mg of iron using mixture of a colorless solution of phosphate iron complex and an emulsifier liquid scintillator. The detection limit was 0.31 Bq (8.4 pCi) per gram iron assuming the counting for 1000 minutes and 95% confidence level. This counting method was applied to determination of55Fe in air-filter samples.
This paper describes a NaI (Tl) scintillation survey meter which can quantify125I on a contaminated surface in situ. This survey meter has four inherent windows; (1) 20-45 keV the singles photopeak region, (2) 45-80 keV the sum photopeak region, (3) 20-80 keV the total photopeak region, and (4) 80 keV-. The activity was calculated based on the sum peak method. The calculated activity of a point source agreed with the standardized source activity within an uncertainty of about 10% both up to the distance of 3 cm from the detector surface along the axis of the detector and on the detector surface. The activity of a simulated plate source also agreed with the source activity within the same uncertainty.