The suitability of cryogenic vacuum extraction for sampling free water (F-water) extracted from environmental materials (grass and soil) was examined with respect to low-level (~ 1 Bq L−1) and precise determination of tritium (3H) concentrations in the extracted water. Tests were conducted using addition-recovery experiments of water containing low 3H activity concentrations (0.43 ± 0.046 Bq L−1) added to dried grass or soil. The results revealed that 3H concentrations in F-water did not significantly differ before and after cryogenic vacuum extraction in both experiments. This suggests that the cryogenic vacuum extraction is useful for sampling F-water to determine 3H concentration in the water.
