Sensitive, precise and accurate methods for determination of low activity level of ⁹⁰Sr and ¹³⁷Cs in grass/vegetable samples by a low background β-counter were developed. The method for ⁹⁰Sr determination was based on coprecipitation as carbonate, elimination of ²¹⁰Bi and iron with a Microthene-TOA column, separation of ⁹⁰Y with a Microthene-HDEHP column, and source preparation as Y₂(C₂O₄)₃. The method for ¹³⁷Cs determination was based on Cs adsorption on ammonium molybdophosphate and precipitation as Cs₃Bi₂I₉ for source preparation. The quality control tests indicated that the methods could provide accurate results. The method application showed that: (1) The mean yields of yttrium and cesium were 79 ± 6% and 84 ± 2%, respectively. (2) The activity concentrations of ⁹⁰Sr in 9 grass/vegetable samples were in the range of 0.04–1.8 Bq kg⁻¹, while that of ¹³⁷Cs in the range of 0.022–0.18 Bq kg⁻¹. And (3) the uptake rate of ⁹⁰Sr from soil to grass/vegetable was much higher than that of ¹³⁷Cs.

开发了灵敏、精确和准确的方法，用于通过低背景 β 计数器测定草/蔬菜样品中⁹⁰ Sr 和¹³⁷ Cs的低活性水平。⁹⁰ Sr 测定方法基于共沉淀为碳酸盐，使用 Microthene-TOA 色谱柱消除²¹⁰ Bi 和铁，使用 Microthene-HDEHP 色谱柱分离⁹⁰ Y，并将源制备为 Y ₂ (C ₂ O ₄ ) ₃ . ¹³⁷ Cs 的测定方法基于 Cs 在磷酸钼铵上的吸附和沉淀为 Cs ₃ Bi ₂ I ₉用于源码准备。质量控制测试表明这些方法可以提供准确的结果。方法应用表明： (1)钇和铯的平均产率分别为79±6%和84±2%。（2）的活性浓度⁹⁰锶在9个草/蔬菜样品在0.04-1.8公斤贝的范围^-1，而的^137个Cs的在0.022-0.18贝公斤的范围^-1。(3) ⁹⁰ Sr 从土壤到草/蔬菜的吸收率远高于¹³⁷ Cs。