Optimization of matrix solid-phase dispersion for the rapid determination of salicylate and benzophenone-type UV absorbing substances in marketed fish

A simple and effective method for the rapid determination of five salicylate and benzophenone-type UV absorbing substances in marketed fish is described. The method involves the use of matrix solid-phase dispersion (MSPD) prior to their determination by on-line silylation gas chromatography tandem mass spectrometry (GC-MS/MS). The parameters that affect the extraction efficiency were optimized using a Box-Behnken design method. The optimal extraction conditions involved dispersing 0.5 g of freeze-dried powdered fish with 1.0 g of Florisil using a mortar and pestle. This blend was then transferred to a solid-phase extraction (SPE) cartridge containing 1.0 g of octadecyl bonded silica (C18), as the clean-up co-sorbent. The target analytes were then eluted with 7 mL of acetonitrile. The extract was derivatized on-line in the GC injection-port by reaction with a trimethylsilylating (TMS) reagent. The TMS-derivatives were then identified and quantitated by GC-MS/MS. The limits of quantitation (LOQs) were less than 0.1 ng/g.