Fig. 1
![90Sr and 90Y decay scheme [4].](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6472612f215d2f6c89dc638c/j_nuka-2022-0006_fig_001.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20251204%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20251204T212101Z&X-Amz-Expires=3600&X-Amz-Signature=ba04fecf95557c397b5da1b30a9281cc0b1c3c390b08f7abb1597e5adbac29de&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 2
Results from the Procorad 2021 proficiency test
| Sample | Reference value (Bq·L−1) | Bateman equation-based procedure (Bq·L−1) |
|---|---|---|
| 21SRB | 3.11 ± 0.17 | 3.28 ± 0.56 |
| 21SRC | 6.06 ± 0.34 | 6.06 ± 1.03 |
Statistical evaluation of the 90Sr recovery in immediate and delayed measurements
| Fortification level (Bq·kg−1) | Immediate | Delayed | ||||||
|---|---|---|---|---|---|---|---|---|
| Mean (%) | Median (%) | SD (%) | n | Mean (%) | Median (%) | SD (%) | n | |
| 5 | 85 | 83 | 10 | 12 | 84 | 83 | 4 | 28 |
| 50 | 82 | 82 | 2 | 12 | 80 | 80 | 3 | 31 |
| Total | 83 | 82 | 7 | 24 | 82 | 81 | 4 | 59 |
Validation characteristics of the applied method
| Characteristics | Result |
|---|---|
| Linearity | 100% |
| MDA | 0.017 Bq·kg−1 |
| Recovery of 90Sr | 82% |
| Relative bias | −18% |
| Repeatability (CV)a | 8.5% |
| Reproducibility (CV)a | 9% |
| Combined standard uncertainty (k = 2)b | 17% |