Simultaneous determination of natural uranium and thorium in food by tri-n-octylamine extraction-spectrophotometric method

Objective: To establish a method which can determine the natural the natural and thorium in food simultaneously. Methods: Based on N235 extraction-spectrophotometric method and chemical similarity between TOA and N235, necessary condition experiments were finished by substituting TOA and N235, the best conditions for the main analytical steps were obtained. By adopting these best conditions, methodological bases of the new analytical procedures were established. The new analytical method has been tested and verified. Results: The lowest detectable limits of the method for Th and U were 3.47 x 10-8 g/g ash and 9.47 x 10-8 g/g ash, respectively. The recovery of standard addition of Th and U were 98.7% and 96.7%, respectively. The relative standard deviation of Th and U were ±5.95% and ±6.31%, respectively. The uranium and thorium contents in main types of food samples were determined with the recoveries between 70% and 90%. Conclusions: The Tri-n-octylamine extraction-spectrophotometric method of simultaneous determination for natural uranium, thorium in food is established for the first time. This method is simple, quick and has good accuracy and precision. (authors)