Extraction, separation, recovery, transportation, ICP-AES trace determination of thorium(IV) with calix[4]resorcinarene-2, 8, 14, 20-tetrakis [N-phenylbenzo]-hydroxamic acid

A novel method for extraction, separation, and trace determination of thorium(IV) with calix[4]resorcinarene-2, 8, 14, 20-tetrakis[N-phenylbenzo]-hydroxamic acid (C4RATHA) is described. The thorium (IV) is extracted from an n-octanol solution of C4RATHA at a pH of 4.5, as colorless extract with a maximum absorption at 375 nm and molar absorptivity of 1.5 × 10⁴ L mol⁻¹ cm⁻¹. The extract is then analyzed using ICP-AES, and a linear calibration graph is obtained between 35.88 and 309.40 ng mL⁻¹ with a detection limit of 20 ng mL⁻¹. The method is applied be used to measure thorium (IV) in monazite sand and rare earth sand in the presence of other diverse ions. The thorium is recovered from seawater and analyzed.