*2.6. Sample Analysis*

A 6890 GC/5975 MSD system (Agilent, Santa Clara, CA, USA) operated in negative chemical ion source/ selective ion monitoring (NCI/SIM) mode and equipped with a 15 m DB-XLB column (0.25 mm, 0.1 μm film thickness, J&W Sciebtific, Folsom, CA, USA) was used for PBDE separation and quantification. The samples (1 μL) were injected in split less mode. Helium was used as carrier gas at a flow rate of 1.2 mL/min, and the temperature program was set as follows: 90 ◦C for 2min, increased to 320 ◦C at 15 ◦C/min and held for 7 min. The temperature of GC inlet, transfer line, ionization source and quadrupole were set at 290 ◦C, 300 ◦C, and 150 ◦C. The compounds were monitored at *m*/*z* 79 and

81 for 3–7 brominated BDEs, *m*/*z* 79, 81, 487 and 489 for BDE-206, 207, 208 and 209, *m*/*z* 474, 476 for 13C-PCB-208, and *m*/*z* 497.6, 499.6 for PCB-209.

Soil pH was measured using a calibrated pH meter (691, Metrohm AG, Herisau, Switzerland) in a weight: volume ratio of 1:10 of soil and tap water, adopting the USEPA method 9054D [36]. Total organic content (TOC) of the soil and dust was determined as the weight loss of dried soil (3 h at 100 ◦C) at 550 ◦C for 5 h [37]. Since PBDEs have a grea<sup>t</sup> potential to bind to environmental matrices rich in organic carbon [38], measuring the TOC concentration in the soil and dust samples was used to establish whether there was any correlation between the measured PBDEs and TOC.
