Abstract
Polycyclic Aromatic Hydrocarbons (PAHs), ubiquitous compounds coming from incomplete combustion processes, are very toxic species and can cause serious effects on the human health. At authors' knowledge, studies on PAHs levels in surface waters are scarce: the main problem regards the analytical implications due to analyzing such compounds at very low levels. This paper would like to present a new extraction protocol based on Dispersive Liquid-Liquid Micro Extraction (DLLME) procedure followed by GC-IT/MS for simultaneous determination of nine PAHs in surface water. Iso-octane is used as extraction solvent whereas no dispersive solvent is involved. An important issue regarded the procedure to obtain the emulsion without dispersive solvent but using ultrasounds; the other important novelty of this method of extraction regards the enrichment factors, that were demonstrated to be significantly high (up to 100,000). Methodological parameters such as the volume of surface water sample, the extraction solvent and relative volume, the time required for breaking emulsion and the salting-out effect have been investigated. Under the optimum experimental conditions (1 L-volume of surface water sample,300 μL of isooctane as extraction solvent, 2 min-ultrasound for the emulsion and 10 minutes-agitation for breaking the emulsion, nitrogen stream for concentrating up to 10 μL, analysis by GC-IT/MS) the method provides very good correlation coefficients (R2 N0.99) in the range investigated, LODs and LOQs able to analyze such compounds in any water matrix (0.001–0.009 pg μL1 and 0.003–0.022 pg μL1, respectively), recoveries ranging 97-109% inter- and intra-day precisions below 6.0% and 8.2%, respectively, for all PAHs. A comparison with other methods reported in literature demonstrates the reliability of such easy, cost-effective and reproducible methods. Finally, applications to nine different water samples are reported and discussed.