Spectrophotometric determination of titanium(IV) by extraction of its thiocyanate complex with cationic surfactants

A spectrophotometric method for the determination of titanium(IV) is described. It is based on the extraction of titanium(IV) as an ion-associated complex, formed between the titanium(IV)-thiocyanate anion and the cetyltrimethylammonium (CTMA), cetylpyridinium (CP), or tetradecyldimethylbenzylammonium (TDMA) cation in chloroform or dichloromethane. Optimum conditions for the extraction and spectrophotometric determination of titanium(IV) by all extractants were determined. The effect of chloride ions on the extraction was also examined. In their presence the systems studied were most sensitive. The apparent molar absorptivities of the complex, at 420 nm, and limit of detection, in the presence of chloride ions, were (6-7) x 10(4) L mol(-1) cm(-1) and 20-35 ng Ti(IV) mL(-1), respectively, depending upon the reagent used. Titanium determination was feasible in the presence of many foreign ions. The ratios of titanium(IV) and CTMA, CP or TDMA determined by Job's method were 1:2. The validity of the method was tested on bauxite and aluminum alloy samples. The values determined were in good agreement with the certified values.