The IAEA-450 CRM is a unicellular microalga (Scenedesmus obliquus). Two batches of algae were grown in an outdoor bioreactor, one batch on a standard nutrient solution (natural contamination level), the second batch on a nutrient solution containing elevated levels of As, Cd, Cr, Hg, Ni, Pb, and Pt. In order toTo adjust the Pt mass fraction to the level of environmental pollution in road dust, the two materials were slurried, mixed in a ratio of 1:100 (high Pt: low Pt) and dried. After homogenization., 10 g units of IAEA-450 were bottled under normal laboratory conditions. After bottling, the material was sterilized by gamma-ray irradiation with a total dose of 25 kGy using a 60Co source according to EN ISO 13485:2003 in an irradiation facility.
Certified values for mass fractions: platinum and trace elements
(based on dry mass)
| Analyte | Certified value* [mg kg-1] | Expanded uncertainty** [mg kg-1] |
| As | 0.102 | 0.007 |
| Cd | 0.158 | 0.010 |
| Cr | 1.48 | 0.12 |
| Hg | 0.104 | 0.012 |
| Ni | 0.82 | 0.10 |
| Pb | 0.98 | 0.07 |
| Pt | 0.074 | 0.004 |
* The certified values are given as total mass fractions of listed elements.
**The uncertainty is expressed as an expanded uncertainty with a coverage factor k = 2 estimated in accordance with the JCGM 100:2008 and ISO 33405.
The certified mass fraction values are based on measurement results obtained from national metrological laboratories using validated methods with known accuracy and established metrological traceability. The certified values were derived by robust statistical methods. Further details are provided in the Certificate.
