TiO2-modified MALDI target for in vitro modeling of the oxidative biotransformation of diclofenac

The UV-induced photocatalytic oxidation in the presence of TiO₂ nanoparticles (UV/TiO₂-PCO) is a more adequate approach than electrochemical oxidation to simulate the oxidative metabolism of diclofenac based on the comparative analysis of oxidation products using high-resolution tandem mass spectrometry. A simple and fast high-throughput technique is proposed for modeling the oxidative metabolism, which involves UV/TiO₂-PCO performed directly on a MALDI target and subsequent analysis by matrix-assisted laser desorption/ionization mass spectrometry. The ranges and yields of diclofenac oxidation products obtained by the conventional bulk UV/TiO₂-PCO and the proposed on-target version are in excellent agreement.