In situ precipitation of hydrous titanium dioxide for dispersive micro solid-phase extraction of nucleosides and their separation

Abstract

Pure titanium dioxide (TiO₂) adsorbent failed to selectively capture ribonucleosides in biological samples, as reported in previous studies, although it was expected to display a specific recognition of cis-diol compounds by the Lewis acid sites on its surface. However, in this work, our results showed for the first time that hydrous titania (TiO₂·nH₂O), obtained through hydrolysis of tetrabutyl titanate (TBOT) in aqueous solution, exhibited a high affinity for cis-diol-containing ribonucleosides. The adsorption efficiency of A, C and G by TiO₂·nH₂O can reach about 90% even in a 100% water matrix. On the other hand, the 2′-deoxynucleosides could only be adsorbed in a water–acetonitrile solution with a water content of less than 10%. Subsequently, an in situ-generated TiO₂·nH₂O-based dispersive micro solid-phase extraction (d-μ-SPE) process was developed and evaluated. The whole d-μ-SPE process takes only about 7 minutes (2 min for extraction and 5 min for centrifugation) and no pre-synthesized or commercial TiO₂ powder is required. The hydrous TiO₂-based d-μ-SPE with a two-step elution strategy was successfully performed for the extraction and separation of ribonucleosides (A, U) and 2′-deoxynucleosides (2′-dC, 2′-dG) in porcine plasma samples. The proposed TiO₂·nH₂O-based d-μ-SPE method is effective, simple and rapid, and will have wide application for the selective extraction of cis-diol molecules in environmental and biological samples.