An Analytical Method to Measure Free-Water Tritium in Foods using Azeotropic Distillation

Abstract

A series of accidents at the Fukushima Dai-ichi Nuclear Power Plant has raised concerns about the discharge of contaminated water containing tritium .3H° from the nuclear power plant into the environment and into foods.In this study, we explored convenient analytical methods to measure free-water 3H in foods using a liquid scintillation counting and azeotropic distillation method,The detection limit was 10 Bq/L, corresponding to about 0.01° of 1 mSv/year.The 3H recoveries were 85-90° in fruits,vegetables,meats and fishes,75-85° in rice and cereal crops,and less than 50° in sweets containing little water.We found that,in the case of sweets,adding water to the sample before the azeotropic distillation increased the recovery and precision.Then,the recoveries reached more than 75° and RSD was less than 10 in all food categories ,13 kinds,Considering its sensitivityprecision and simplicity, this method is practical and useful for 3H analysis in various foods, and should be suitable for the safety assessment of foods. In addition,we examined the level of 3H in foods on the Japanese market,No 3H radioactivity was detected in any of 42 analyzed foods.