Synthesis of doubly labeled polyacrylic acid with 14C and 3H

Polyacrylic hydrogels were 14C- and 3H-labeled in three main steps. In the first one, the monomer as sodium salt was 14C-labeled at the carboxyl group via the carbonation of vinylmagnesium bromide and [1-14C]acrylic acid was obtained, followed by labeling with tritium via isotopic exchange in heterogeneous catalysis. The monomer was purified and its radiochemical purity was analyzed using TLC. In the last step, the hydrogel was obtained through radiopolymerization of the doubly labeled monomer using a 60Co source. The oligomers and unpolymerized monomers were eliminated from the hydrogel by swelling in water followed by dehydration with methanol. (author)