Optimization and validation of a chromatographic methodology for the quantification of PAHs in drinking water samples

Polycyclic aromatic hydrocarbons (PAHs) are one of the most important persistent organic toxic micropollutants present in water. These compounds are essentially known for their carcinogenic, mutagenic and genotoxic properties, especially the PAHs containing four or more aromatic rings. The determination of these compounds in water is a challenging situation, making it necessary to develop specific methods with very low detection limits. This work describes the optimization and validation of a methodology for the determination of the five PAHs proposed in the Portuguese legislation, using a solid phase extraction technique followed by a reverse-phase high performance liquid chromatography with fluorescence detection: benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[ghi]perylene, indene[1,2,3-cd]pyrene and benzo[a]pyrene. The performance of the methodology was tested in terms of linearity, limits of detection and quantification, trueness, repeatability and intermediate precision, following the recommendations of the international standard ISO-IEC 17025. The method showed good linearity for the tested concentration range, with limits of detection less than 0.29 ng-L for all the PAHs. Analytical recoveries, repeatability and intermediate precision were calculated in ultra-pure, bottled and tap water, with recoveries values ranging from 80 to 110%, repeatability and precision RSD values less than 15%. The methodology was applied to real water samples, fifty water springs from Sintra municipality. In the samples analyzed, PAHs were detected under the limits proposed by the legislation.