Titanium-dioxide nanotubes as sorbents in (micro)extraction techniques

• We summarize the use of titanium-dioxide nanotubes (TDNTs) as sorbents.
• We describe the main properties and the ways of synthesizing TDNTs.
• We explain the main applications of TDNTs in SPE and SPME.
• We outline future trends in the use of TDNTs as sorbents in (micro)extraction.

Titanium-dioxide nanotubes (TDNTs) are elongated nanomaterials with a large specific surface area and notable features, such as inertness, chemical and thermal stability. This overview focuses on the use of TDNTs as sorbents in sample preparation. After a brief introduction to their properties and structure, we describe the main routes of synthesis for the laboratory production of TDNTs. These routes, which comprise electrochemical, chemical-template and hydrothermal approaches, mark the ultimate application of this nanomaterial. Finally, we present the usefulness of TDNTs in solid-phase extraction (SPE), micro-SPE and solid-phase microextraction contexts on the basis of the published literature.