Magnetic solid-phase extraction of caffeine from surface water samples with a micro-meso porous activated carbon/Fe 3 O 4 nanocomposite prior to its determination by GC-MS.

A novel micro-meso porous activated carbon/Fe 3 O 4 (Bm) composite was synthesized from the active charcoal precursor BAX-1500 and used in the magnetic solid-phase extraction (MSPE) of caffeine prior to its determination by gas chromatography-mass spectrometry (GC-MS). The main factors affecting the extraction and desorption steps of the MSPE procedure were investigated and optimized. These factors include extraction time, sorbent mass and salt addition for the adsorption step and type of eluent, desorption time and volume of desorption solution for the desorption step. Under optimum conditions, the absolute extraction recovery was found to be 91.1% and good linearity was observed in the investigated concentration range of 0.6-12.5 ng mL -1 ( R 2 = 0.9997). The limit of detection was 0.18 ng mL -1 and the limit of quantification was 0.60 ng mL -1 . The method was successfully applied to the analysis of surface water samples. The proposed MSPE method is simple, rapid, sensitive and environmentally friendly.