Trace analysis of benzophenone-derived compounds in surface waters and sediments using solid-phase extraction and...

This study describes a procedure for determining eight benzophenone-derived compounds in surface waters and sediments. These include the pharmaceutical ketoprofen, its phototransformation products 3-ethylbenzophenone and 3-acetylbenzophenone, and five benzophenone-type ultraviolet (UV) filters. The proposed analytical method involves the pre-concentration of water samples by solid-phase extraction (SPE) and microwave-assisted extraction (MAE) of sediment samples followed by derivatization and analysis by gas chromatography-mass spectrometry. Different parameters were investigated to achieve optimal method performance. Recoveries of 91 to 96 % from water samples were obtained using HLB Oasis SPE cartridges, whereas MAE of sediments (30 min at 150 °C) gave recoveries of 80 to 99 %. Limits of detection were between 0.1 and 1.9 ng L(-1) for water samples and from 0.1 to 1.4 ng g(-1) for sediment samples. The developed method was applied to environmental samples and revealed the presence of UV filters in the majority of the surface waters with up to 690 ng L(-1) of 2-hydroxy-4-methoxybenzophenone. By contrast, ketoprofen (≤2,900 ng L(-1)) and its degradation products (≤320 ng L(-1)) were found in only two rivers, both receiving wastewater treatment plant effluents. Sediment analysis revealed benzophenone to be present in concentrations up to 650 ng g(-1), whereas concentrations of other compounds were considerably lower (≤32 ng L(-1)). For the first time, quantifiable amounts of two ketoprofen transformation products in the aqueous environment are reported.