2.2 Sampling with stir bar sorptive extraction
SBSE devices were cleaned in a TDU C200 conditioner (Gerstel) at 300 °C under a nitrogen flow of 100 mL min-1 for two hours and kept in closed chromatography glass vials containing inserts with metal springs (Gerstel) until application on the sampling spots. For sampling, the devices were positioned on specific sites of the steel construction and the wall. In order to avoid direct contact with the wall or steel tubes aluminum foil were placed between the magnetic SBSE devices and the steel part. For sampling of the cross section of the room a tape was fixed on the ground and SBSE devices were placed on top of it as outlined in Fig. 1. Room temperature and air humidity were monitored using a VoltCraft DL-121 TH Multidata Logger. After the respective exposition time, SBSE devices were collected and put into the vials for transport to the laboratory and stored until analysis under repeatability conditions on the last day of each sampling campaign.