A new concept of hollow fiber liquid–liquid–liquid microextraction compatible with gas chromatography based on two immiscible organic solvents

A new concept of liquid–liquid–liquid microextraction (LLLME) was introduced based on applying two immiscible organic solvents in lumen and wall pores of hollow fiber (HF). With this methodology, analytes of interest can be extracted from aqueous sample, into a thin layer of organic solvent (dodecane) sustained in the pores of a porous hollow fiber, and further into a μL volume of organic acceptor (acetonitrile or methanol) located inside the lumen of the hollow fiber. Some chlorophenols (CPs) were selected as model compounds for developing and evaluating of the method performance. The analysis was performed by gas chromatography–electron capture detection (GC–ECD) without derivatization. The factors affecting the HF-LLLME of target compounds were investigated and the optimal extraction conditions were established. Under the optimum conditions, preconcentration factors in a range of 208–895 were obtained. The performance of the proposed method was studied in terms of linear dynamic ranges (LDRs from 0.02 to 100 ng mL−1), linearity (R2 ≥ 0.995), precision (RSD % ≤ 8.1) and limits of detection (LODs in the range of 0.006–0.2 ng mL−1). In addition to preconcentration, HF-LLLME also served as a technique for sample clean-up.