Sensitive method for titanium determination in soil extract using adsorptive stripping voltammetry

Wide application of TiO₂ results in contamination of the environment, and may cause adverse changes in the soil. Monitoring of soil for pollution with both solid and ionic (mobile) forms of Ti seems to be a need. Therefore, it is necessary to develop an alternative method to ICP-MS for determining ionic Ti at low concentration. Electrochemistry is particularly promising, as only the ionic form is determined, and with high precision. Adsorptive stripping voltammetry with differential pulse mode, utilizing complexation with mandelic acid supported by the catalytic effect of chlorate (V) ions, is presented here for determination of Ti in unmodified extract of soil rich in organic matter. The proposed procedure allows to detect 0.01 ng mL^-1 in voltammetric cell, which gives 3 ng mL^-1 for peat soil extracts (t_d = 240 s) with precision <1.5%. The studies indicated that 0.3 ng of Ti(IV) in cell is quantified with 100-101% recovery. The procedure optimized for such a challenging matrix can be included in complex studies of the content of ionic and solid forms of titanium compounds in soils.