First Order Derivative Spectrophotometric Determination of Thorium in Geological Samples Using Diacetylmonoxime p-hydroxybenzoylhydrazone

Abstract

A simple, selective and sensitive spectrophotometric method has been developed for the determination of trace amounts of thorium using a newly synthesised reagent diacetylmonoximep-hydroxybenzoylhydrazone (DMPHBH) in the presence of Triton X-100. The molar absorptivity and Sandell’s sensitivity of the coloured species at pH 4.4 were found to be 4.20 x 104 L mol-1 cm-1 and 5.5 ng cm-2, respectively. Beer’s law is obeyed in the range 0.35 -3.8 mg mL-1 of thorium(IV) at 410 nm. The stoichiometry of the complex was found to be 1:2 (Th(IV): DMPHBH). A highly selective first order derivative spectrophotometric method for the determination of thorium in the presence of uranium is also reported. The detection limit and quantitation limit of first order derivative spectrophotometry were found to be 0.03 and 0.11 mg mL-1, respectively. The developed procedure has been successfully applied for the trace level determination of thorium in rock samples and synthetic mixtures.