Solid phase microextraction based on polypyrrole films

Abstract

Polypyrrole (PPY, with different N-substituents or with different counter ions) films were prepared and applied for solid-phase microextraction (SPME). The extraction properties of the new films to volatile organic compounds were examined using an SPME device coupled with GC/FID. A PPY coated capillary was applied for in-tube SPME to evaluate its extraction efficiency towards less volatile compounds and ionic species. The porous surface structures of the films, revealed by scanning electron microscopy (SEM), provided high surface areas and allowed for high extraction efficiency. Compared with commercial SPME stationary phases, the new phases showed better selectivity and sensitivity toward polar, aromatic mbasic and anionic compounds, due to their inherent multifunctional properties. In addition, introducing a new functional group, such as phenyl group in poly-N-phenylpyrrole (PPPY), or incorporating an appropriate counter ion into the polymer could modify the extraction efficiency and selectivity of the films for SPME. For in-tube SPME, the PPY coated capillary showed superior extraction efficiency to commercialcapillaries for a variety of compounds, demonstrating its potential applications for a wide range of analytes when coupled with HPLC. The sensitivity and selectivity of the films for SPME could also be tuned by changing the film thickness. The preliminary results of a study on electrochemically controlled SPME demonstrated that the unique electroactivity and reversible redox property of polypyrrole films could be used to further improve the selectivity and sensitivity of SPME by controllibng the applied electrochemical potentials. These results are in line with both the theoretical expectations and the results obtained by other methods, which indicate not only that PPY films can be used as new stationary phases for SPME, but also that SPME method may provide an alternative tool for studying materials like polypyrrole.