Sensitive microspectrophotometric determination of thorium(IV) and uranium(VI) with pyrogallol red in presence of cationic surfactant

摘要

Formation of water soluble deeply colored ternary complexes of Th~(IV) and U~(VI) metal ions with pyrogallol red (PGR) in presence of cationic surfactant cetyldimethylethylammonium bromide (CDMEAB) have been observed. CDMEAB sensitize the color reactions of Th~(IV) and U~(VI) with pyrogallol red with enhancement in molar absorptivities and sensitivities at the shifted wavelength of ternary complexes with stoichiometric composition 1:2:4 (M-PGR-CDMEAB) have been observed for both the metal ions. The ternary complexes of thorium(IV) ar pH 4.0 and uranium(VI) at pH 7.0 exhibit absorption maxima at 660 and 650 nm with molar absorptivities 61120 and 52470 L mol~(-1) cm~(-2) respectively. Beer's law were obeyed in concentration range 0.23-3.24 ppm for Th~(IV) and 0.27-3.51 ppm for U~(VI) in presence of CDMEAB. Conditional formation constants and various analytical parameters have been evaluated and compared the results of newly formed ternary complexes with binary complexes reported earlier. Enhancement in the molar absorptivities in presence of CDMEAB clearly indicated the usefulness of these colored reactions for microdetermination.