ISO 2 2125-2 standard Part 2 specifies a test method for the determination of strontium-99 (Sr-99) isotopes in water quality using Inductance Coupled Plasma Mass Spectrometry (ICP-MS). This method is suitable for the accurate measurement of strontium-99 in water quality monitoring, especially in the fields of environment pollution monitoring and nuclear waste treatment. Sensitivity ICP-MS technology can detect strontium-99 content in water samples, providing an effective means for assessing the impact of radioactive substances on water quality. The implementation of this standard can help ensure that radioactive substances in water bodies are within safe limits, safeguarding public health and environmental safety.