空白采样膜中^(210)Po含量及其对样品分析的影响

Content of ^(210)Po in Blank Aerosol Sampling Membrane and Its Influence on Sample Analysis

分析了4种不同材质2种常用尺寸规格的气溶胶采样膜中^(210)Po的含量。结果表明,国产玻璃纤维膜和聚丙烯膜中^(210)Po的含量较高,且这2种采样膜在日常监测中采用最多。通过测定玻璃纤维膜中铀含量可知,^(210)Po偏高主要是由生产膜的原材料引起的。通过实际样品测定与相对合成标准不确定度的估算,量化地分析了空白采样膜对实际气溶胶样品测定的影响。玻璃纤维膜A、B(分别为国内A、B厂家生产)和聚丙烯膜A(国内A厂家生产)材质的单张采样膜中^(210)Po含量与气溶胶样品中^(210)Po含量的比值较高,对分析结果的影响不能忽略,因此建议,在分析^(210)Po含量大于30mBq的气溶胶样品时,要扣除空白采样膜中^(210)Po含量。当气溶胶中^(210)Po含量低至几十μBq/m3水平时,扣除空白采样膜后的测定结果不确定度较大,应选取^(210)Po含量较低的采样膜(如石英纤维材质)。

In this paper,four kinds of aerosol sampling membranes made of different materials with two kinds of commonly used size specifications were analyzed,and the contents of 210 Po were given.The results show that the contents of 210 Po in domestic glass fiber membrane and polypropylene membrane are higher,and the two sampling membranes are the most widely used in daily monitoring.By measuring the uranium content in the glass fiber membrane,it is known that the high content of 210 Po is caused by the raw material for producing the membrane.The influences of blank sampling membrane on the determination of actual aerosol samples were quantitatively analyzed by actual sample determination and relative synthesis standard uncertainty estimation.The ratios of 210 Po content in the single sampling membrane of the glass fiber membranes A and B(produced by domestic A and B manufacturers)and polypropylene membrane A(produced by domestic A manufacturers)to that in the aerosol samples are higher.The influence of the determination results cannot be ignored.Therefore,it is recommended to deduct the 210 Po content in the blank sampling membrane when analyzing aerosol samples with 210 Po content greater than 30 mBq.When the 210 Po content in the aerosol is as low as tens ofμBq/m 3,the uncertainty of the measurement result is large after subtracting the blank sampling membrane,and a sampling membrane with a low content of 210 Po(such as quartz fiber material)should be selected.