Comparison of two methods for determination of low level 137 Cs activity concentration in food sample
Objective To study the applicability of conventional detection method,gamma spectrometry and radiochemical analysis,for the determination of 137Cs activity concentratons in food samples and to compare the difference of such two methods for this purpose.Methods By using both γspectrometry and radiochemical analysis,the activity concentrations of 137Cs in different types of food were determined,to compare the required sample amounts,the sample pretreatment and preparation processes and the lower detection limits.With meat samples as a case study,the two method were compared for assessing the activity concentrations of 137Cs in meat samples and evaluating the uncertainties.Results The deviation of measurement result obtained in meat by using gamma spectrometry and ammonium phosphomolybdate-β counting method is consistent,with relative extended uncertainties of 18.0％and 8.0％,respectively.The pretreatment process for γ spectrometry is characterized by its simplicity,but large sample amount required and time-comsuming process,while the ammonium phosphomolybdate method requires a small amount of sample but in need of separation and purification process.The detection limits of the two methods are 10.6 mBq/kg(sample mass 11.7 kg)and 5.1 mBq/kg(sample sample 2.1 kg),respectively.Conclusions The results of two methods for determinationf of the low activity concentrations of 137 Cs in food samples are consistent.Therefore,when monitoring low activity concentrations of 137Cs in food samples,the appropriate detection method can be selected based on the specific objective and requirements of the monitoring study.
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