水质 镭 226 使用 ICP-MS 的测试方法

[中文适用范围]： 本文件规定了通过电感耦合等离子体质谱 (ICP-MS) 测定 226Ra 浓度的方法。获得的质量浓度可以转换成活性浓度。该方法适用于饮用水、雨水、地表水和地下水样品的测试，经过适当的采样和处理以及测试样品制备。检测限取决于样品体积、所用仪器、背景计数率、检测效率、计数时间和化学收率。使用现有设备，本文件所述方法的检测限约为10 mBq·l-1，优于WHO饮用水安全饮用标准（1 Bq·l-1）。该方法涵盖了水中 226Ra 活度浓度在 0.001 Bq·l−1 和 100 Bq·l−1 之间的测量。如果进行稀释，则可以测量浓度高于 1 Bq·l−1 的样品。本文档中描述的方法适用于紧急情况。在该方法中，测试样品的过滤是必要的。该方法不包括对悬浮物吸附的 226Ra 的分析。不溶部分的分析需要矿化步骤，本文件未涵盖该步骤。在这种情况下，对获得的不同相进行测量。用户有责任确保该测试方法对于测试的水样的有效性。 [外文原描述]： This document specifies methods to determine 226 Ra concentration by inductively coupled plasma mass spectrometry (ICP-MS). The mass concentrations obtained can be converted into activity concentrations. The method is applicable to test samples of drinking water, rainwater, surface and ground water, after proper sampling and handling, and test sample preparation. The detection limit depends on the sample volume, the instrument used, the background count rate, the detection efficiency, the counting time and the chemical yield. The detection limit of the method described in this document, using currently available equipment, is approximately 10 mBq·l -1 , which is better than the WHO criteria for safe consumption of drinking water (1 Bq·l -1 ). This method covers the measurement of 226 Ra in water at activity concentrations between 0,001 Bq·l −1 and 100 Bq·l −1 . Samples with concentrations higher than 1 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. In this method, filtration of the test sample is necessary. The analysis of 226 Ra 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.