2.4.2. Extraction of organic micropollutants from water
Collected water samples were kept in closed brown glass bottles at 4 °C until their analysis within two weeks. Octadecylsilane cartridges were conditioned by successive elution of 3 mL of methanol and 3 mL of water, by gravity. Then, a volume of 100 mL of lake water sample, previously filtered through a 0.45 μm pore-size nylon disc, was eluted with the help of a vacuum pump. Cartridges were dried with a stream of nitrogen for about 30 min and, finally, they were eluted with 1 mL of dichloromethane, which was injected in the chromatographic system.
2.4.3. Extraction of organic micropollutants from sediment
Moisture of the sediments was removed by extending them on filter paper and leaving them for about 48 h at room temperature in darkness. They were sieved to pass a 2 mm screen and kept in closed paper bags at 4 °C until their analysis within two weeks.
An amount of 3 g of dry sediment was placed in a 14 mL glass vial and a volume of 10 mL of a 3:7 (v/v) mixture of n-hexane and dichloromethane was added. The vial was closed and mechanically shaken for 20 min. After separating the phases by decantation, the liquid phase was collected with a pipette and the solid phase was again extracted with an aliquot of 10 mL of the n-hexane/dichloromethane mixture. Then, the liquid phase was collected and combined with the previous one. The extract was evaporated heating at 30 °C under a gentle stream of nitrogen and the dry residue was dissolved in 1 mL of dichloromethane. Finally, the extract was filtered through 0.50 μm pore-size PTFE, being ready for injection.