Solvent Extraction, Sequential Separation and Trace Determination of La (III), Ce (III), Nd (III) and Gd (III) with 2, 14-bis[m-nitrophenyl]-Calix[4]Resorcinarene-8, 20-bis[N- phenylbenzo]-dihydroxamic Acid

ABSTRACT A novel reagent 2,14-bis[m-nitrophenyl]-calix[4]resorcinarene-8,20-bis[N-phenylbenzo]-dihydroxamic acid (NPC4RADHA) is reported for the liquid-liquid extraction, separation, and simultaneous trace determination of La(III), Ce(III), Nd(III), and Gd(III). The method involves optimizing various parameters such as the concentration of NPC4RADHA, pH, solvent, and extraction time to achieve maximum purity (99.98%) extraction of these rare earths. The stability constant, molar absorptivity, and Beer’s law have been studied. The extracted samples were directly analyzed by ICP-AES, which improves sensitivity with determination limits of 0.020 ng/mL, 0.028 ng/mL, 0.018 ng/mL and 0.025 ng/mL for La, Ce, Nd, and Gd, respectively. The method has been applied to the determination of these elements in monazite sand and standard geological samples. The separation and determination mixture of a Ce(III) and Ce(IV) has been reported.