Development of a simultaneous pressurised-liquid extraction and clean-up procedure for the determination of UV filters in sediments

A useful tool for the determination of eight UV filters in sediments which combines extraction and clean-up in a single-step has been developed. To this end, the protocol incorporates silica gel and copper powder placed directly in the pressurised-liquid extraction (PLE) cell. After extract evaporation, salicylate- and benzophenone-type UV filters are derivatised with N,O-bis-trimethylsilyltrifluoroacetamide (BSTFA). Trimethylsilylation increases the sensitivity of these UV filters about 4-10-fold when they are finally analysed by gas chromatography-mass spectrometry (GC-MS). Derivatisation conditions (temperature, time and volume of BSTFA) and PLE parameters (temperature, time, number of cycles and solvent composition) were optimised using multivariate experimental designs. Under optimal conditions, the developed procedure provides an excellent linearity, detection limits (1-5 ng g⁻¹) and recoveries above 73% for all the compounds. Compared to the few existing methods, this analytical approach affords optimal throughput and method automation. Finally, the proposed method was applied to the analysis of three sediment samples.