Polypyrrole coated capillary coupled to HPLC for in tube solid phase microextraction and analysis of aromatic compounds in aqueous samples

In-tube solid-phase microextraction (SPME) based on a polypyrrole (PPY)-coa ted capillary was investigated for the extraction of aromatic compounds fro m aqueous solutions. The PPY-coated capillary was coupled on-line to HPLC t hat was programmed with an autosampler to achieve automated in-tube SPME an d HPLC analysis, Three groups of aromatics, including both polar and nonpol ar compounds, were examined, The results demonstrated that the PPY coating had a higher extraction efficiency than the currently used commercial capil lary coatings, especially for polycyclic aromatic compounds and polar aroma tics due to the increasing pi-pi interactions, interactions by polar functi onal groups,and hydrophobic interactions between the polymer and the analyt es, In addition to the functional groups in the PPY coating, which contribu ted to the higher extraction efficiency and selectivity toward analytes, th e coating's porous surface structure,which was revealed by electron microsc opy experiments, provided a high surface area that allowed for high extract ion efficiency, It was found that the extraction efticiency and selectivity could be tuned by changing the coating thickness. The preliminary study of the extraction mechanism indicated that analytes were extracted onto the P PY coating mainly by an adsorption mechanism. The method was used for the e xtraction and analysis of both polar and nonpolar aromatics in aqueous samp les.