A certified reference material designed for the determination of 129I in seawater, IAEA-418 (Mediterranean Sea water) is described and the results of certification are presented. The median
of 129I concentration with 95% confidence interval was chosen as the most reliable estimates of the true value. The median, given
as the certified value, is 2.28 × 108 atom L−1 (95% confidence interval is (2.16–2.73) 108 atom L−1), or 3.19 × 10−7 Bq L−1 (95% confidence interval is (3.02–3.82) × 10−7 Bq L−1). The material is intended to be used for standardization procedures applied in accelerator mass spectrometric laboratories.
It is available in 1 L units and may be ordered via IAEA web side (www.iaea.org).