Sample preparation based on matrix solid-phase dispersion and solid-phase extraction cleanup for the determination of...

A method based on matrix solid-phase dispersion (MSPD) and SPE to determine 20 organochlorine pesticides (OCPs) in fish tissues (muscle and liver) was optimized in terms of the sorbents and elution solvents used for the analysis. The following analytical components were evaluated: ENVI-CarbTM and ENVI-18 as dispersing agents, Florisil and Florisil over alumina as cleanup adsorbents, and hexane and hexane-ethyl acetate (80 + 20) as elution solvents. The pesticides were determined by GC with electron capture detection. The best results were obtained with ENVI-Carb as a dispersing agent and an ENVI-Florisil co-column using 40 mL hexane-ethyl acetate (80 + 20) as the elution solvent. Analytical recoveries ranged between 75 and 130% except for beta-HCH in fish liver, and the RSD values were < 15% for most of the pesticides studied. Furthermore, sensitivity was sufficient (LOD of < 300 microg/kg) for all OCPs under study, in compliance with the tolerance limits of the U.S. Food and Drug Administration for OCPs in fish. The results were compared with those obtained by microwave-assisted extraction (MAE) and pressurized liquid extraction (PLE) in order to evaluate the performance of the MSPD procedure. The MPSD methodology was shown to be easy to use and fast, with a clear advantage relative to cost, because it does not need the expensive equipment required for MAE and PLE.