Phoenix 40

The on-line LC-GC instrument (LC-GC 9000, Brechbühler, Zurich, Switzerland) consisted of a Phoenix 40 with three syringe LC pumps and four switching valves and an UV/VIS detector (UV-2070 Plus, Jasco, Japan). The autosampler was a PAL LHS2-xt Combi PAL (Zwingen, Switzerland). The LC column was a 25 cm × 2.1 mm i.d Lichrospher Si 60, 5 μm (DGB, Schlossboeckelheim, Germany). The GC was a Trace GC Ultra from Thermo Scientific (Milan, Italy).
A gradient, starting with hexane (0.1 min) and reaching 30% of dichloromethane (at 300 µL/min) in 0.5 min, was used to elute the MOSH (from 2.0 to 3.5 min) and the MOAH (from 4 to 5.5 min) as described by Biedermann et al. (2009) . separation column coated with a 0.15 μm film of PS-255 (1% Vinyl, 99% Methyl Polysiloxane) (Mega, Italy). A rapid oven gradient (40 °C min -1 ) starting from 55 °C up to 350 °C was used for GC analysis (Barp et al., 2013) . The FID and the SVE were heated at 360 °C and 140 °C, respectively. After the transfer, the LC column was backflushed (dichloromethane) and reconditioned prior to the subsequent injection.