本文件规定了使用液体闪烁计数（LSC）测定所有类型水样品中铁55（55Fe）活性浓度的试验方法。使用当前可用的液体闪烁计数器，该测试方法可以测量55Fe放射性浓度，范围从检测限到120 mBq l-1。对于0.5 l至1.5 l的样品体积，可在7200 s至10800 s之间的计数时间内获得这些值。可通过稀释样品或使用较小的样品等份或两者来测量较高的活性浓度。注:这些性能指标完全取决于各个实验室的测量制度；特别是，检测限受稳定铁含量的影响。 应用范围取决于水中溶解物质的数量和测量设备的性能特征（背景计数率和计数效率）。 实验室有责任确保本试验方法适用于所测试的水样。购买本文件时可获得的所有当前修订均包含在购买本文件中。

This document specifies a test method for the determination of iron-55 (55Fe) activity concentration in samples of all types of water using liquid scintillation counting (LSC). Using currently available liquid scintillation counters, this test method can measure the55Fe activity concentrations in the range from the limit of detection up to 120 mBq l-1. These values can be achieved with a counting time between 7 200 s and 10 800 s for a sample volume from 0,5 l to 1,5 l. Higher activity concentrations can be measured by either diluting the sample or using smaller sample aliquots or both.NOTEThese performance indicators are wholly dependent on the measurement regimes in individual laboratories; in particular, the detection limits are influenced by amount of stable iron present. The range of application depends on the amount of dissolved material in the water and on the performance characteristics of the measurement equipment (background count rate and counting efficiency). It is the laboratory's responsibility to ensure the suitability of this test method for the water samples tested.All current amendments available at time of purchase are included with the purchase of this document.