The material was obtained from the “Vladimirovka” collective farm, Polesskoe, Kiev, Ukraine, in summer 1990. The material was air dried and milled to less than 0.35 mm by the Brjansk Centre for Agricultural Radiology and Chemistry. 100 kg of the bulk material were recombined and homogenized at the IAEA Terrestrial Environment Laboratory by mixing the powder in a 300 liter drum for 72 hours. The material density was measured in 13 test portions and found to be 0.778 ± 0.001 g/cm3. Bottling of IAEA-330 was carried out under normal laboratory conditions, taking all precautions to avoid segregation. Portions of 100 g were dispensed into plastic bottles sealed with security polyethylene caps and labelled with the code IAEA-330. After bottling the material was sterilized by gamma ray irradiation with a total dose of 25 kGy using a Co-60 source according to EN ISO 13485:2003 to ensure long-term stability of the material by inhibiting microbial action.
Reference date for decay correction: 2007-10-15
| Radionuclide | Certified Value Bq kg-1 | Uncertainty* Bq kg-1 |
| 40K | 1188 | 30 |
| 90Sr | 20.1 | 2.1 |
| 137Cs | 1235 | 34 |
| 234U | 1.02 | 0.07 |
| 238U | 0.95 | 0.05 |
(*) Uncertainty is expressed as a Mixture model median based standard deviation S (MM-median) at 95 % confidence level.
The certified values listed above were established on the basis of results reported by the IAEA Terrestrial Environment Laboratory in Seibersdorf, Austria. Five expert laboratories from Finland, Hungary, Republic of Korea and Portugal analysed the IAEA-330 spinach material. Each laboratory received three bottles and was asked to determine the measurands of interest in each bottle. The obtained results from the expert laboratories were used to confirm the IAEA reference values. In total 30 and 15 bottles were analysed in the Terrestrial Environment Laboratory and expert laboratories respectively during the characterization campaign of the spinach material. The IAEA derived reference values were in good agreement with the expert laboratories results.
References
[1] International Atomic Energy Agency (2009): Worldwide Open Proficiency Test on the Determination of Radionuclides in Spinach, Soil and Water, IAEA-CU-2007-03, IAEA Analytical Quality in Nuclear Applications Series No. 8 (report attached).
