Enhancing micro-scale membrane extraction by implementing a barrier film

Hollow fiber based microextraction techniques have shown much promise in the extraction and preconcentration of analytes. Typically, a solvent held in the membrane is used as an extractant (or an acceptor). However, the acceptor also permeates out during long extractions and vigorous agitation. The stabilization of the acceptor is important for high enrichment and good reproducibility. Coating the membrane with a low permeability barrier film can provide diffusional resistance to reduce the outflow of the acceptor. Several compounds were evaluated as potential barrier films. They were found to protect the organic acceptor and significantly enhance extraction performance. In a study with six polycyclic aromatic hydrocarbons (PAHs), enrichment factors ranged between 494 and 4555 were obtained and the detection limits were at low ppb to ppt levels. Good reproducibility with RSDs between 1.60 and 7.65%, and large linear dynamic ranges with good linearity (R2 between 0.9870 and 0.9997) were also achieved.