ISO 4723:2023 水的质量 锕-227 使用α光谱的试验方法

标准编号：ISO 4723:2023

中文名称：水的质量 锕-227 使用α光谱的试验方法

英文名称：Water quality — Actinium-227 — Test method using alpha-spectrometry

发布日期：2023-11

标准范围

本文件规定了通过α光谱法测定所有类型水中227Ac活度浓度的测试方法。本试验方法适用于供水/饮用水、雨水、地表水和地下水、海水以及冷却水、工业用水、生活和工业废水的试验样品，经过适当的取样和处理以及试验样品制备（参见ISO 5667-1、ISO 5667-3、ISO 5667-10）。需要过滤供试品。检测限取决于样品体积、使用的仪器、背景计数率、检测效率、计数时间、化学产率和子代向内生长。本文中描述的方法使用当前可用的α光谱测定装置，具有大约0.03？Bq·l？1，当直接测量227Ac的α峰时。该检测限低于世卫组织对任何锕系元素α发射体的饮用水安全饮用标准（0,1？Bq·l？1）.[4]计数时间为48？h对于样品体积为1？l.只有一小部分227Ac通过α发射衰变（~1.42？%）.降低该方法检测限的一种选择是等待，让227Ac的后代生长，并测量227Ac的α后代峰（例如215Po）。这是一种较长的技术，但检测下限约为0,000？2？Bq·l？1可通过将样本重新计数约90？纯化后几天。样本可以在90之前重新计数？天，但具有更高的检测限。本文件中描述的测试方法可用于计划的、现有的和紧急暴露情况，也可用于废水和液体流出物，并进行特定修改，以增加总体不确定性、检测限和阈值。对于紧急情况，优选减少计数时间而不是样品体积。吸附在悬浮物上的227Ac的分析不在本文件中。

This document specifies a test method to determine the activity concentration of ²²⁷Ac in all types of waters by alpha spectrometry.

The test method is applicable to test samples of supply/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 (see ISO 5667-1, ISO 5667-3, ISO 5667-10). Filtration of the test sample is necessary.

The detection limit depends on the sample volume, the instrument used, the background count rate, the detection efficiency, the counting time, the chemical yield, and the progeny ingrowth. The method described in this document, using currently available alpha spectrometry apparatus, has a detection limit of approximately 0,03 Bq·l^？1, when directly measuring the alpha peak of ²²⁷Ac. This detection limit is lower than the WHO criteria for safe consumption of drinking water for any actinide alpha emitter (0,1 Bq·l^？1).^[4] This value can be achieved with a counting time of 48 h for a sample volume of 1 l.

Only a small fraction of ²²⁷Ac decays through alpha emissions (~1,42 %). An option to lower the detection limit of the method is to wait, let the progenies of ²²⁷Ac grow in, and measure an alpha progeny peak of ²²⁷Ac (e.g. ²¹⁵Po). This is a longer technique, but a lower detection limit of approximately 0,000 2 Bq·l^？1 can be obtained by re-counting the sample approximately 90 days after purification. The sample can be re-counted before 90 days, but with a higher detection limit.

The test method(s) described in this document can be used during planned, existing and emergency exposure situations as well as for wastewaters and liquid effluents with specific modifications that can increase the overall uncertainty, detection limit and threshold. For an emergency situation, it is preferable to reduce the counting time rather than the sample volume.

The analysis of ²²⁷Ac adsorbed to suspended matter is not covered by this document.

标准预览图