Complexation equilibria and spectrophotometric determination of thorium(IV) with Lawsone.
The complex equilibria of Th4+ with Lawsone (2-hydroxy-1,4-naphthoquinone, LAS) were studied spectrophotometrically in 40% (v/v) ethanol water at 25 degrees C and an ionic strength of 0.1 M (NaClO4). The absorbance graphs were analysed to demonstrate and characterize the complex forming equilibria. A simple, rapid, selective and sensitive method for the spectrophotometric determination of trace amounts of thorium(IV) is developed. The complex formed at pH 2.1-3.6 (epsilon = 0.27 x 10(4) cm2 mol-1, at lambda = 440 nm) allows the determination of 5.8-32 micrograms/ml thorium. The effect of interferences was studied.
al-Nady
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AB
Chemistry Deprtment, Faculty of Science, Assiut University, Assiut, Egypt. elnady@yahoo.com
al-Shaibi
Y
Y
Ba-Issa
A
A
Ariqui
W
W
D000042:Absorption; D004396:Coloring Agents / Q000737:chemistry*; D009285:Naphthoquinones / Q000737:chemistry*; D013053:Spectrophotometry / Q000379:methods; D013910:Thorium / Q000032:analysis / Q000737:chemistry*
D004396:Coloring Agents; D009285:Naphthoquinones; D013910:Thorium; C005090:lawsone