A procedure of separation and preconcentration for titanium determination in seawater samples by ICP-OES

In the present paper, a procedure for separation, preconcentration and determination of trace amounts of titanium in seawater samples by using inductively coupled plasma optical emission spectrometry (ICP-OES) has been proposed. It is based on the complexation of titanium(IV) ions by 4-(2-thiazolylazo)-orcinol (TAO) and hydroxylamine chlorhydrate reagents and its sorption onto activated carbon. Parameters such as: pH effect on the complexation and sorption, TAO amount, hidroxylamine chlorhydrate amount, shaking time, mass of activated carbon, desorption of titanium from activated carbon, sample volume, effect of other ions and analytical features were studied. Results demonstrated that the titanium(IV) ions, within the pH range from 3.8 to 7.0, as TAO complex, has been quantitatively recovered (90-110%) onto activated carbon. The TAO amount required was 1.0 mg and the hidroxylamine chlorhydrate amount was 20.0 mg.The shaking time required for sorption was 5 min by using 100 mg of activated carbon. A successfully desorption of titanium for its determination by ICP-OES was achieved by heating the loaded activated carbon with 3 mol L-1 nitric acid solution because is strongly adsorved the complex. The precision of the procedure, calculated as the relative standard deviations were 4.7 and 2.5% for titanium concentrations 1.0 and 2.5 mu g L-1 , respectively. The limit of detection was 0.01 mu g L-1 , for a sample volume of 400 mL, considering the achieved enrichment factor of 80. The method was tolerant to other ions usually present in seawater samples. The procedure was applied to determine this element in seawater samples collected in beaches of the cities of Arembepe and Salvador, Bahia-Brazil.