To obtain the highest possible sensitivity, the MS detection was
operated using time-scheduled selected ion monitoring (SIM)
based on the selection of the mass peaks with the highest
intensities for each compound. In the SIM mode, the following
important ions are used for the selected VOCs: m/z 91 and 92 for
toluene, m/z 91, 106 for ethyl benzene, o-xylene and m-xylene.