A sample of about 350 kg of mixed fish species was collected in the eastern Irish Sea by the Center for Environment, Fisheries and Aquaculture Science (CEFAS), Lowestoft, U.K., in 1996. The skin was removed, the fish filleted, freeze-dried and subsequently sent to IAEA-MEL for processing. The sample, which was reduced by freeze-drying to about 69 kg, was ground to powder, sieved through a 0.5 mm mesh and homogenized by mixing in a nitrogen atmosphere. The sample was freeze-dried once more, ground and sieved at 250 μm, and a final amount of 10 kg obtained. The sample was then mixed with 100 kg of North Sea fish powder (fraction below 250 μm). To ensure homogenization of the final sample, both samples were mixed by jet pulverizing in a nitrogen atmosphere. The samples were packed into bottles under nitrogen gas, sealed with polyethylene caps and labeled with the code IAEA-414. The bottles containing 100 g of fish powder each were sterilized by gamma ray irradiation with a total dose of 25 kGy using a 60Co source according to ISO 13485:2003 to ensure long-term stability of the material by inhibiting microbial action.
Reference date for decay correction: 2019-01-01
Certified values (based on dry mass)
| Radionuclide | Certified value | Unit | Expanded uncertainty |
| 40K | 480 | Bq/kg | 22 |
| 137Cs | 3.09 | Bq/kg | 0.07 |
| 232Th | 0.0290 | Bq/kg | 0.0022 |
| 234U | 1.22 | Bq/kg | 0.06 |
| 235U | 0.0500 | Bq/kg | 0.0042 |
| 238U | 1.11 | Bq/kg | 0.07 |
| 238Pu | 0.019 | Bq/kg | 0.002 |
| 239+240Pu | 0.120 | Bq/kg | 0.005 |
| 241Am# | 0.231 | Bq/kg | 0.025 |
*The uncertainty is expressed as an expanded uncertainty using a coverage factor k = 2 estimated in accordance with the JCGM 100:2008 'Evaluation of measurement data - Guide to the expression of uncertainty in measurement' [1] and ISO Guide 35 [2].
•Americium-241 values should be corrected for ingrowth from 241Pu.
The values listed above were established on the basis of statistically valid results submitted by laboratories which had participated in an international interlaboratory comparison organized by the IAEA Marine Environment Laboratories, Monaco. The details concerning the criteria for qualification as certified or information value may be found in the report IAEA/AL/145 (attached).
