Sample Preparation before Voltammetric Determination of Ionic Form of Ti(IV) in Organic-Rich Matrix - Critical Point of Analysis

The applicability of adsorptive stripping voltammetry with hanging mercury drop electrode (HMDE) electrode has been studied for the determination of the ionic form of Ti(IV) in samples requiring specific pretreatment and decomposition of the organic matrix before measurement. Application of the mixture of conc. HNO₃ and conc. HCl (3:4) for sample decomposition in a closed microwave system using two-stage program with a maximum temperature 210°C, and next dilution in solution preventing hydrolysis, containing 0.05 mmol L⁻¹ KClO₃ and 0.24 mmol L⁻¹ mandelic acid in deionized water (supporting electrolyte) allows to determine single ng of Ti(IV) in the plant leaves extract and fertilizer containing significant amounts of inorganic salts, surface compounds, and chelates. Determination was done after short deposition (t_d = 60–90s, E_d = −0.150 V) with negative-going potential scan. The method was validated by the recovery study of Ti at the ng level (complete recovery – 102%).