GB/T 35189-2017 in English

1. Background and significance of the standard

GB/T 35189-2017 "β counting method for the determination of iodine-131 in marine organisms" is the first method standard for the determination of radioactive isotope iodine-131 in marine organisms in my country. This standard was proposed by the State Oceanic Administration to standardize the analysis process of iodine-131 in marine biological samples and ensure the accuracy and reliability of the data.

2. Principle and technical route of the method

Low background β measurement instrument is the core instrument of this standard. Through the pretreatment steps of sample fixation, ashing, leaching, extraction and precipitation, the silver iodide (AgI) precipitation source is finally prepared, and the β decay characteristics of ¹³¹I are used for radioactivity analysis.

3. Reagent and instrument requirements

The standards have extremely strict specifications for reagents and instruments. For example, the low background β meter requires that the background count rate is no higher than 0.15 counts/(cm²·min) at 2π efficiency. In addition, the analytical balance must be accurate to 0.1 mg to ensure the accuracy of sample processing.

4. Comparison of standard frameworks and technological evolution

Compared with earlier standards such as GB/T 13272-1991 and GB/T 13273-1991, GB/T 35189-2017 has achieved breakthroughs in the following aspects:

• The self-absorption correction method of ¹³¹I was introduced, which significantly improved the measurement accuracy.
• The sample pretreatment process was optimized, and the chemical recovery rate was increased from 65% to more than 70%.
• For the first time, the online monitoring technology of ¹³¹I has been realized in the field of marine life.

5. Implementation suggestions and precautions

To ensure the effective implementation of the standard:

1. The laboratory needs to be equipped with professional personnel to ensure that the operation complies with safety regulations.
2. Regularly calibrate the instruments, especially the low background β meter and analytical balance.
3. It is recommended to deduct the self-stable iodine content in the high iodine sample to avoid high chemical recovery rate.