水质.锝-99.第1部分:使用液体闪烁计数的试验方法

[中文适用范围]： 本文件规定了通过液体闪烁计数 (LSC) 测量所有类型水中 99Tc 的方法。 该方法适用于供水/饮用水、雨水、地表水和地下水以及冷却水、工业用水、生活和工业废水经过适当取样和处理以及测试样品制备后的测试样品。 测试样品的过滤是必要的。 检测限取决于样品体积和所使用的仪器。 本文件描述的方法使用目前可用的LSC仪器，检测限约为5 Bq·kg−1至20 Bq·kg−1，低于WHO饮用水安全饮用标准（100 Bq·kg−1） −1)[3]。 对于 14 ml 至 40 ml 之间变化的样品体积，可以通过 30 分钟的计数时间获得这些值。 本文件中提出的方法不适用于超痕量 99Tc 的测定。 本文件中的活性浓度值以样品质量单位表示，而不是类似标准中通常采用的样品体积单位。 原因是 99Tc 是在淡水或海水等各种基质类型中测量的，这些基质类型的密度存在显着差异。 通过测量样品体积，可以轻松地将活性浓度值转换为样品体积单位。 然而，它增加了活性浓度结果的不确定性。 本文件中描述的方法适用于紧急情况，但不适用于 99mTc 的存在量可能造成干扰的情况，以及不适用于 99mTc 用作恢复示踪剂的情况。 该方法不包括对悬浮物吸附的 Tc 的分析。 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 a method for the measurement of 99 Tc in all types of waters by liquid scintillation counting (LSC). The method is applicable to test samples of supply/drinking water, rainwater, surface and ground water, as well as cooling water, industrial water, domestic, and industrial wastewater after proper sampling and handling, and test sample preparation. A filtration of the test sample is necessary. The detection limit depends on the sample volume and the instrument used. The method described in this document, using currently available LSC instruments, has a detection limit of approximately 5 Bq·kg −1 to 20 Bq·kg −1 , which is lower than the WHO criteria for safe consumption of drinking water (100 Bq l −1 ) [3] . These values can be achieved with a counting time of 30 min for a sample volume varying between 14 ml to 40 ml. The method presented in this document is not intended for the determination of ultra-trace amount of 99 Tc. The activity concentration values in this document are expressed by sample mass unit instead of sample volume unit as it is usually the case in similar standards. The reason is that 99 Tc is measured in various matrix types such as fresh water or sea water, which have significant differences in density. The activity concentration values can be easily converted to sample volume unit by measuring the sample volume. However, it increases the uncertainty on the activity concentration result. The method described in this document is applicable in the event of an emergency situation, but not if 99m Tc is present at quantities that could cause interference and not if 99m Tc is used as a recovery tracer. The analysis of Tc adsorbed to suspended matter is not covered by this method. It is the user's responsibility to ensure the validity of this test method for the water samples tested.