GB/T 35188-2017 in English
VALIDDetermination of 131 I in marine sediment―β counting method
- Issued on:2017-12-29
- Implemented on:2018-04-01
- File Format:PDF
- Delivery:Via email within 1~3 business days
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《GB/T 35188-2017海洋沉积物中碘-131的测定 β计数法》由TC283（全国海洋标准化技术委员会）归口，主管部门为自然资源部(海洋)。
Introduction
Interpretation of GB/T 35188-2017, the national standard of the People's Republic of China
Background and purpose of the standard
GB/T 35188-2017 "Determination of iodine-131 in marine sediments by beta counting method" is to standardize the detection method of radioactive nuclide iodine-131 in marine environmental monitoring. 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. It aims to provide a scientific and accurate analysis method for evaluating the level of radioactive contamination in marine sediments.
The standard was drafted based on the rules given in GB/T1.1-2009, which meets the national needs for marine environmental protection and radioactive detection. The consistency and accuracy of the data are ensured by standardizing the steps of sample collection, processing, and analysis.
Method principle and technical path
Iodine-131 mainly releases energy through β decay, and its branching ratios are 89.2%, 7.27% and 2.1%, corresponding to energies of 0.606 MeV, 0.334 MeV and 0.248 MeV, respectively. These β particles can be effectively detected using a low-background β meter.
The detection steps include sample preparation, leaching, extraction, precipitation and source preparation, and finally measurement on a low-background β meter. The specific process is as follows: Mixed alkali fixation → high-temperature calcination → leaching → sodium hypochlorite oxidation → sodium nitrite reduction → carbon tetrachloride extraction → back extraction → silver iodide precipitation → source preparation → β counting.
Actual application case
In a certain marine environmental monitoring, this standard was used to detect the iodine-131 content in sediment samples. By precisely controlling the parameters of each step, accurate specific activity data can ultimately be obtained, providing a scientific basis for environmental protection decisions.
Reagents and Instrument Specifications
| Category | Name | Specifications | Precautions |
|---|---|---|---|
| Reagents | Potassium iodide (KI) | Analytically pure | Need to be stored away from light |
| Instrument | Low background β meter | Use 90Sr−90Y β source, 2π efficiency ratio not less than 50% | Requires regular calibration |
| Equipment | Muffle furnace | Temperature control range: room temperature to 1000℃ | Must be used in a well-ventilated environment |
Comparative analysis of standard frameworks
| Dimensions | GB/T 35188—2017 | Reference standard GB 17378.3 | ASTM D4785—2008 |
|---|---|---|---|
| Scope of application | Determination of 131I in marine sediments | Sample collection, storage and transportation | Analysis of iodine isotopes in water |
| Principle of the method | β counting method | Radioactivity measurement | Chemical separation and β counting |
| Detection limit | 2.78 Bq/kg (95% confidence level) | - | 0.1 μCi/L |
Implementation recommendations and precautions
To ensure the accuracy and reliability of the test results, it is recommended that:
- Operators should receive professional training and be familiar with radiation protection knowledge.
- Strictly control the experimental conditions in accordance with the standard requirements, especially in the sample preparation and reagent use.
- Regularly calibrate the instrument to ensure the accuracy of detection efficiency.
- Strengthen blank tests and quality control to eliminate abnormal data in a timely manner.
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