Left: experimental (pe  +  pH_m) values determined for the Pu samples containing hydroquinone (HQ, blue symbols) or Sn(II) (red symbols) as redox buffers. Right: R_d values determined for the uptake of Pu by C–S–H 1.4 in the absence and presence of gluconate at pH  =  13.3. All experiments performed at S:L  =  1 g dm⁻³. DL stands for detection limit (courtesy of R. Guidone et al. Empa (Switzerland) and KIT (Germany)).