低水平环境水样中^(90)Sr含量的测定

Measurement of ^(90)Sr Content in Low-level Environmental Samples

为了加强对低于国标规定的探测下限(10 mBq/L)的低水平环境水样中90Sr含量的监测,对国标GB6766—1986《水中90Sr放射化学分析方法二-(2-乙基己基)磷酸萃取色层法》中90Sr含量测定条件进行了优化和细化。以P204树脂为分离柱分离90Sr和90Y,观察了水样取样体积,水样、探测效率和电镀源校正测量时在低本底α、β测量仪上测量时间的选择,水样前处理时加入饱和草酸溶液和调溶液pH先后顺序对形成沉淀的影响。测量条件优化后,探测下限可达到0.36 mBq/L,低于国标规定的测量下限10 mBq/L;对低水平环境水样中90Sr含量测量的加标回收率为89.8%～124.0%。以上结果说明,测量条件优化后,方法的准确度良好,可达到对低水平环境水样中90Sr含量(含低水平水样)准确测量的目的。

This research focuses on the optimization of analysis conditions for 90Sr in water sample using extraction chromatography method by di-（2-ethylhexy） phosphoric acid based on GB 6766—1986,and makes this method more suitable for 90Sr analysis in environmental water samples with the specific activity lower than 10 mBq/L.In optimized analysis process the P204 resin column was used in separating 90Y from 90Sr-90Y mixture,and the sampling volume as well as the β counting time for the measurements of water samples,detecting efficiency,calibration with electroplating source were optimized.The measurement of 90Sr content in an actual low-level environmental water sample was performed,by optimized extraction chromatography method,and the results showed that the full process recovery was 89.8%-124.0% and the detecting limit to 90Sr was 0.36 mBq/L,which was lower than 10 mBq/L in GB 6766—1986.