title: The surfactant sensitized analytical reaction of cerium(IV) with some triphenylformazan derivatives.
abstract: Cationic surfactant, cetylpyridinium bromide (CPB), sensitizes the colour reaction of cerium(IV) with 1,3-o-hydroxyphenyl-5-phenylformazan(I), 1-m-hydroxyphenyl-3-o-hydroxyphenyl-5-phenylformazan(II) and 1-m-carboxyphenyl-3-o-hydroxyphenyl-5-phenylformazan(III). The formation of a soluble ternary complex of stoichiometric ratio 1:1:1 (Ce(IV)-R-CPB) is responsible for the observed enhancement in the molar absorptivity and Sandell sensitivity of the formed complex, when a surfactant is present. The ternary complex exhibits absorption maxima at 596, 571 and 607 nm (epsilon=6.05 x 10(4), 6.28 x 10(4) and 8.06 x 10(4)L mol(-1)cm(-1)) using triphenylformazan derivatives I, II and III, respectively. Beer's law is obeyed between 0.15 and 2.5 microg ml(-1), whereas, optimum concentration range applying Ringbom method is in the range 0.30-2.25 microg ml(-1). Conditional formation constants in the presence and absence of CPB for Ce(IV) complexes have been calculated. The proposed method has been successfully applied to the analysis of magnesium-base cerium alloys and synthetic mixtures corresponding to various cerium alloys.
authors.affiliation: Chemistry Department, Faculty of Science, Benha University, Benha, Egypt. isahmed61@yahoo.com
authors.forename: I S
authors.initials: IS
authors.lastname: Ahmed
authors.forename: A S
authors.initials: AS
authors.lastname: Amin
authors.forename: Y M
authors.initials: YM
authors.lastname: Issa
mesh_terms: D000497:Alloys / Q000032:analysis; D002563:Cerium / Q000737:chemistry*; D002594:Cetylpyridinium / Q000737:chemistry*; D005562:Formazans / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D013501:Surface-Active Agents / Q000737:chemistry*; D013696:Temperature; D013997:Time Factors
chemical_list: C512103:1,3-o-hydroxyphenyl-5-phenylformazan; C512105:1-m-carboxyphenyl-3-o-hydroxyphenyl-5-phenylformazan; C512104:1-m-hydroxyphenyl-3-o-hydroxyphenyl-5-phenylformazan; D000497:Alloys; D005562:Formazans; D013501:Surface-Active Agents; D002563:Cerium; D002594:Cetylpyridinium