Identification of photocatalytic degradation products of bezafibrate in TiO2 aqueous suspensions by liquid and gas chromatography

In the present study the photocatalytic degradation of bezafibrate (BZF), a lipid regulator agent, has been investigated using TiO2 suspensions and simulated solar light. The study focus on the identification of degradation products (DPs) using powerful analytical techniques such as liquid chromatography time of flight mass spectrometry (LC–TOF–MS), gas chromatography mass spectrometry (GC–MS), and high-performance liquid chromatography with diode-array detection (HPLC–DAD). Each technique provided complementary information that enabled the identification of 21 DPs. Accurate mass measurements obtained by LC–TOF–MS provided the elucidation of 17 DPs. Mass errors lower than 2 mDa, allowed the assignment of empirical formula for the mayor DPs to be determined confidently. Three DPs were identified by GC–MS through the structural information provided by full scan mass spectra obtained by electron impact (EI) ionization and two more by HPLC–DAD by comparing the retention times (tR) and the UV spectra of the unknown DPs with those of commercial standards. Based on this by-product identification a possible multi-step degradation scheme was proposed. The pathways include single or multiple hydroxylation of BZF with subsequent phenoxy ring opening and the cleavage of the amide and ether bonds.