title: Solid phase extractive preconcentration of thorium onto 5,7-dichloroquinoline-8-ol modified benzophenone.
abstract: The preparation of solid reagent 5,7-dichloroquinoline-8-ol modified benzophenone for preconcentration of thorium is described. The thorium-5,7-dichloroquinoline-8-ol complex is quantitatively retained on benzophenone in the pH range 6.0-6.5. The solid mixture consisting of the metal complex together with benzophenone is dissolved in 5 ml of acetone and thorium content was established spectrophotometrically by using Arsenazo III procedure. Calibration graphs are rectilinear over the thorium concentration range 0.001-0.2 mug ml(-1). Five replicate determinations of 20 mug of thorium present in 1 l of sample solution gave a mean absorbance of 0.320 with a relative standard deviation of 2.9%. The detection limit corresponding to three times the standard deviation of the blank was found to be 0.0005 mug ml(-1). The developed procedure has been successfully utilized for the estimation of thorium content of pure Rare earth chloride solution collected from Indian Rare Earths (IRE) Limited, Alwaye.
authors.affiliation: Inorganic and Analytical Chemistry Group, Regional Research Laboratory, CSIR, Trivandrum 695 019, Kerala, India.
authors.forename: C R
authors.initials: CR
authors.lastname: Preetha
authors.forename: J Mary
authors.initials: JM
authors.lastname: Gladis
authors.forename: T Prasada
authors.initials: TP
authors.lastname: Rao