Application of gas chromatography-tandem mass spectrometry to the analysisof inhibition of dimerisation of tributylphosphate under radiolysis - Identification of isomeric tributylphosphate-alkylbenzene inhibitor coupling products

Tributylphosphate (TBP), solvent used as extractant for reprocessing spent nuclear fuel, can dimerise under radiolysis. This occurs by radical radical recombination, leading to 10 isomeric dimers (TBP-TBP). These species are complexation agents and are responsible of fission product retention in the organic phase that increases the solvent degradation. In order to limit th eir formation two free radical inhibitors (In), isopropyl and 1,4-diisoprop ylbenzenes, were used. These additives reduce by about 50% the concentratio n of TBP-TBP dimers but this reduction is not strictly followed by TBP rege neration as mixed coupling products from TBP and inhibitor are detected. By using GC-MS-MS and selectively deuterated compounds, the identification of these different isomers (TBP-In) has been realised. From these identificat ions and from the analysis of the proportion of the different isomers, the major primary TBP radical generated under radiolysis was determined. (C) 20 01 Elsevier Science B.V. All rights reserved.