Spectrophotometric determination of titanium with o-carboxyphenylfluorone in cationic micellar media, and its equilibrium and kinetic studies

Spectrophotometric determination of titanium(IV) was accomplished with o-carboxyphenylfluorone (OCPF) in the presence of hexadecyltrimethyl ammonium chloride (HTAC) under strongly acidic media. In the determination of titanium(IV), Beer's law was obeyed in the range of 24-340 ng mL^-1 with an effective molar absorption coefficient (at 530 nm) and relative standard deviation of 2.24 × 10⁵ dm³ mol^-1 cm^-1 and 0.64% (n = 8), respectively. The severe interference of iron ions was easily eliminated by the addition of ethylenediaminetetraacetic acid (EDTA); the effects of other foreign substances were low. Equilibrium and kinetic studies under analytical conditions were investigated to quantitatively evaluate the reaction mechanism. The obtained orange complex is considered to be Ti(OCPF)₄. Its stability log K_f and rate constant K _obs are 16.88 and 1.65 × 10^-2 s^-1, respectively. It is suggested that the color of the complex is related to the species of OCPF in the solution.