水质钍232第2部分:ICP-MS试验方法

[中文适用范围]： 本文件规定了用等离子体质谱法（ICP-MS）测定钍 \(232\left(2^{32} \mathrm{Th}\right)\) 的方法。所获得的质置浓度可以转换为活度浓度。本文档中描述的方法适用于饮用水、雨水、地表水和地下水、海水以及冷却水、工业水、生活和工业废水经过适当采样和处理后以及测试样品制备后的检测。检出限取决于样品体积、使用的仪器、背景计数率、检测效率和化学产率。在本文件中，使用当前可获得的设备的方法的检出限约为 \(2 \mathrm{mBq}^{-1}\)（或 \(\mathrm{mBq}^{-1} \mathrm{~g}^{-1}\)），低于 WHO 对饮用水安全消费的标准 \(\left(1 \mathrm{~Bq}^{-1}\right)^{}\)。本文档描述的方法覆盖了在 \(2 \mathrm{mBq}^{-1}\) 到 \(5 \mathrm{~Bq} \cdot \mathrm{l}^{-1}\) 的活度浓度下对 \({ }^{232} \mathrm{Th}\) 进行测量。活动浓度高于 \(5 \mathrm{~Bq} \cdot \mathrm{l}^{-1}\) 的样品可以通过稀释进行测量。本文档描述的方法在紧急情况下适用。测试样品的过滤对于本文档中描述的方法是必要的。对悬浮物质吸附的 \({ }^{232} \mathrm{Th}\) 分析不包括在本方法中。分析不可溶部分需要一个未涵盖本文件的矿化步骤。在这种情况下，测量是在获得的不同相上进行的。确保本测试方法对测试的水样有效是用户的职责。 [外文原描述]： This document specifies a method to determine thorium 232 ( 232 Th) by inductively coupled plasma mass spectrometry (ICP-MS). The mass concentrations obtained can be converted into activity concentrations. The method described in this document is applicable to test samples of drinking water, rainwater, surface and ground water, marine water, as well as cooling water, industrial water, domestic and industrial wastewater after proper sampling and handling and test sample preparation. The limit of detection depends on the sample volume, the instrument used, the background count rate, the detection efficiency and the chemical yield. In this document, the limit of detection of the method using currently available apparatus is approximately 2 mBq·l −1 (or mBq·kg −1 ), which is lower than the WHO criteria for safe consumption of drinking water (1 Bq·l −1 ) [ 4 ] . The method described in this document covers the measurement of 232 Th in water at activity concentrations between 2 mBq·l −1 and 5 Bq·l −1 . Samples with higher activity concentrations than 5 Bq·l −1 can be measured if a dilution is performed. The method described in this document is applicable in the event of an emergency situation. Filtration of the test sample is necessary for the method described in this document. The analysis of 232 Th adsorbed to suspended matter is not covered by this method. The analysis of the insoluble fraction requires a mineralization step that is not covered by this document. In this case, the measurement is made on the different phases obtained. It is the user’s responsibility to ensure the validity of this test method for the water samples tested.