Portable micro-solid phase extraction for the determination of polycyclic aromatic hydrocarbons in water samples

This work describes for the first time the application of portable micro-solid phase extraction (μ-SPE) for the determination of polycyclic aromatic hydrocarbons (PAHs). In this technique, a battery-operated electric whisk stirrer combined with a μ-SPE device was employed to provide agitation of the sample solution and facilitate the pre-concentration of the target analytes. The μ-SPE device consisted of multi-walled carbon nanotubes (MWCNTs) packed in a polypropylene (PP) membrane. The performance of μ-SPE sampling coupled with high performance liquid chromatography-ultraviolet detection (HPLC-UV) was evaluated for the analysis of five target PAHs (fluorene, anthracene, fluoranthene, pyrene and benzo[a]pyrene) in water. Important μ-SPE parameters were studied and the optimal extraction conditions were 30 min extraction time, 10 min desorption time, isopropanol as the conditioning and desorption solvent and no addition of a salt. The developed portable μ-SPE method provided good linearity in the concentration range of 0.1-100 μg L-1 for fluorene, anthracene, fluoranthene and pyrene, and 1-100 μg L-1 for benzo[a]pyrene, with good coefficients of determination (r2, 0.9975-0.9989), low limits of detection (0.01-0.59 μg L-1), acceptable intra-day precisions (3.5-6.2% for on-site analysis) and acceptable relative recoveries (77.3-107.2%). Portable μ-SPE combined with HPLC-UV was successfully applied to the determination of target PAHs in selected water samples. The proposed sample preparation technique proved to be simple, cost effective, easy-to-operate and feasible for both off-site and on-site analyses