对常规测定矿泉水中总α及总β放射性时须在两份样品中分别操作并测量的方法作了改进,即只取一份样品,同时测量其中的总α和总β.方法的主要改进在于将矿泉水样品(1~5 L,预先用少量盐酸酸化)蒸发至干,使其中放射性物质浓集于残渣中.将在100 ℃烘干的残渣于450 ℃灰化2 h,冷至室温准确称得其质量.残渣中的放射性源应满足厚于有效厚度和少于最大取样量的要求.测量时间对检出限和测定的相对偏差有明显影响的因素也进行了讨论.

The conventional methods for the determination of radioactivity of total α and total β in mineral water was improved by using only one portion of sample instead of taking two separate portions in the usual procedures,and by performing the determination of total α and total β simultaneously.The radio active isotopes in mineral water sample (1 to 5 L,acidified with a small amount of HCl previously) were pre-concentrated in the residue remained after evaporation with H2SO4 to dryness.The residue was ashed at 450 ℃ for 2 h,and its mass was taken accurately.Radio active source in the residue should conform to the rules of “thicker than the effective thickness” and “less than the maximum quantity of sample taken”.Time of measuring an influential factor to both the detection limit and the relative deviation of determination,was also discussed.