Dynamic three-phase hollow fiber microextraction based on two immiscible organic solvents with automated movement of the acceptor phase

Dynamic three-phase hollow fiber liquid liquid liquid microextraction (HF-LLLME) based on two immiscible organic solvents, with automated movement of organic acceptor phase to facilitate mass transfer was introduced for the first time. Polycyclic aromatic hydrocarbons were used as model compounds and extracted from water and soil samples. The extraction involved filling an 8 cm length of hollow fiber with 25 mu L of organic acceptor solvent using a microsyringe, followed by impregnation of the pores in the fiber wall with n-dodecane. The fiber was then immersed in 20 mL of aqueous sample solution. During extraction, the organic acceptor phase was repeatedly moved in the lumen of the hollow fiber by movement of the syringe plunger controlled by programmable syringe pump. Following this microextraction, 2 mu L of organic acceptor phase was injected into gas chromatography-flame ionization detector. This new technique provided up to 554-fold preconcentration of the analytes under the optimized conditions. Good repeatabilities (with RSDs <= 8.4%) were obtained. Detection limits were in the range of 0.2-0.5 mu g/L. The utilization of the proposed method for extraction of the polycyclic aromatic hydrocarbons from different real samples (such as water and soil samples) also gave good precision and recovery.