Application of Self-Assembled Monolayers in the Preparation of Solid-Phase Microextraction Coatings

Self-assembled monolayers (SAMs) of polyaminithiophenol (PATP) were used as a covalent bonded coating for solid-phase microextraction (SPME). Thiolated aniline-analog monomers (mixture of 2- and 3-aminothiophenols, 2/3-ATP) were anchored on the gold surface and then electropolymerized. Due to the strong S-Au bond, thiol-terminated coating on the gold surface was very stable. The proposed covalent bonded coating showed higher mechanical (re-usability up to 100 times) and thermal stability (up to 320 A degrees C) than non-covalent bonded polyaniline coating (re-usability up to 20 times and thermal stability up to 250 A degrees C). The extraction capability of the proposed fiber for the extraction of five polycyclic aromatic hydrocarbons (PAHs), including phenanthrene, anthracene, pyrene, 9,10-dimethylanthracene and benzo[alpha]anthracene was examined. The effects of different parameters influencing the extraction efficiency of analytes including extraction temperature, extraction time, ionic strength, stirring rate and sample volume were examined and optimized. Linear ranges of 1-250 mu g L-1 for phenanthrene and anthracene, and 1-100 mu g L-1 for the other compounds were obtained. Detection limits were in the range of 0.1-0.32 mu g L-1. Single fiber repeatability and fiber to fiber reproducibility were less than 8.9 and 15.8%, respectively. Seawater sample was analyzed as real sample and good recoveries (81-108%) were obtained for target analytes.