Approach for independent-matrix removal of polycyclic aromatic hydrocarbons from solid samples based on microwave-assisted Soxhlet extraction with on-line fluorescence monitoring

A flow injection interface for fluorometric monitoring of focused microwave -assisted Soxhlet extraction (FMASE) is presented. This assembly allows rea l-time on-line monitoring of the PAHs extracted from solid samples in each Soxhlet cycle and provides qualitative and semiquantitative information fro m natural and spiked samples. Hence, the extraction kinetics can be followe d and the end of the leaching step determined independently of the sample m atrix, thus avoiding excessive extraction times, The research also involves the study of the multivariate effects of the FMASE parameters by a central composite design. The method was applied to a certified reference material (CRM 524, BCR, industrial soil/organics) for quality assurance/validation. The total content of each analyte was determined by HPLC-fluorometric dete ction, and the results obtained demonstrated that FMASE is a technique as e fficient as conventional Soxhlet to extract PAHs from soils but with a dras tic reduction of both extraction time and organic solvent disposal.