Protonation of the amine group is unlikely at the pH values of the samples since the values of pKa for the three N groups of DTPA are 6, 7, and 8. However, it has been shown that radiolysis products can cleave N-C and other bonds in ethylamine, triethylamine, and a diamide phenanthroline extractant. It has also been reported that hydrated electrons and OH radicals induce the release of lanthanide and other ions from EDTA (ethylene diamine tetraacetic acid), a complexant similar in structure to DTPA. A comparable attack of DTPA by aqueous radiolysis products would result in a loss of the coordination ability of the complexant.