GB/T 35570-2017 in English

Background and Significance of the Standard

GB/T 35570—2017 "Determination of Xenon in Seawater by Low Background Liquid Scintillation Spectrometry" is a detection method for trace radioactive nuclides in the marine environment. The standard was proposed by the State Oceanic Administration, and the main drafting unit was the South China Sea Environmental Monitoring Center of the State Oceanic Administration.

With the construction and operation of coastal nuclear facilities, the impact of trace radioactive substances in seawater on the environment and human health has attracted much attention. The formulation of this standard aims to provide an efficient and accurate detection method to ensure the scientificity and standardization of marine ecological environment monitoring work.

Method Principle and Technical Advantages

Low-background liquid scintillation spectrometry is a technique based on the analysis of the characteristic β-ray energy spectrum of radionuclides. Its core is to use liquid scintillator to convert β particles in the sample into fluorescent signals, and analyze the fluorescent signals through the spectrometer to determine the activity concentration of specific nuclides in the sample.

Compared with traditional methods, this technology has the following advantages:

• High sensitivity: suitable for the detection of ultra-trace radioactive substances;
• High efficiency: short measurement time and accurate results;
• Strong adaptability: suitable for samples with different concentration ranges.

Instrument and reagent requirements

According to standard 5.1, the core instrument is a < b>low-background liquid scintillation spectrometer, whose detection efficiency is not less than < strong >25%, and the background count rate is < strong >0.005~0.02 counts per second. In addition, auxiliary equipment such as vacuum distillation device and conductivity meter are also included.

In terms of reagents, standard 4 requires the use of high-purity reagents and standardized scintillation liquid. Among them, < strong >PPO and POPOP are key ingredients to improve fluorescence efficiency and detection sensitivity.

Analysis steps and quality control

Standard 7 specifies the sample pretreatment, preparation and measurement process in detail. Including:

1. Sample collection and storage: According to GB17378.3-2007, stored in glass bottles at room temperature;
2. Distillation desalination: Use a vacuum distillation device to remove impurities and salts;
3. Electrolytic enrichment: Suitable for pretreatment of low-concentration samples;
4. Scintillation fluid preparation: Prepare immediately before use to ensure optimal performance.

In terms of quality control, Standard 10 emphasizes:

• Operators need to be specially trained;
• Instruments and equipment are calibrated and maintained regularly;
• Data recording and storage comply with specifications.

Implementation Suggestions and Outlook

To ensure the effective implementation of the standard, it is recommended to:

• Strengthen personnel training and improve operational skills;
• Optimize equipment configuration and improve detection efficiency;
• Establish a regional monitoring network to achieve regular monitoring.

In the future, as the demand for marine environmental monitoring increases, it is recommended to further study and promote:

• Automated sampling system;
• New scintillator formula;
• Online detection technology.