The distribution of plutonium between the mineral and organic components of rat bone: a biochemical study after in vivo and in vitro contamination

Abstract

Purpose: To measure the distribution of plutonium between the mineral and organic components of rat bone after chemical extraction of powdered bones, 48 h after contamination of rats with 238Pu-citrate. Materials and methods: Chemical extractions were performed by EDTA treatment or by formic acid followed by guanidine treatments. The extracts were analysed for proteins and Pu content after chromatography experiments. Complementary experiments have been performed, mainly the addition of citrate and/or Pu to the formic acid medium during the extraction of contaminated or uncontaminated bones. Results: EDTA extracted most of the Pu in an ultrafilterable form. By contrast, formic acid extracted only about 20% of Pu, whereas the remaining Pu was solubilized by guanidine. Gel permeation chromatography showed that it was mostly associated with 20-40 kD macromolecules. The high affinity of these macromolecules for Pu was confirmed after in vitro contamination of dialysed EDTA extracts. The complementary experiments suggested that deposition of the solubilized Pu on the residue during the formic acid treatment might occur, and showed that the amount of extracted Pu increased by adding citrate. Conclusion: The results show that the initially observed distribution of Pu in mineral (20%) and organic (80%) bone matrix may be in error due to Pu deposition on the organic residue during the extraction procedure.