“…It is noteworthy that up to 10 molecules of nitric acid per macrocycle can be extracted from the aqueous to the organic phase. 3,8,124,125 The effect of concentration of nitric and picric acids on the extraction of strontium, 87, 102 ± 104, 119 uranium, 105,107,114,126,127 1.25 and 3.0 mol litre 71 , respectively. For the U 6+ ion, the D U increases as the concentration of HNO 3 is increased and reaches a plateau for its concentration of 5 ± 8 mol litre 71 (Refs 105, 114).…”