Air Monitoring: New Advances in Sampling and Detection

Figure 11

500 mL of a 4 ppb level hydrocarbon standard collected on a multi-bed tube using a piston pump and analysed by TD-GC/MS (TD-100, Markes International Ltd), using a quadrupole mass spectrometer (full scan, blue; SIM, red) and a TOF mass spectrometer (black—BenchTOF-dx ALMSCO International Ltd, UK). Table inset shows the root-mean-square (RMS) signal-to-noise ratio (S/N) for isoprene using the ion at m/z 67. The inset shows extracted-ion m/z 67 for 260 pg of isoprene on column, showing excellent peak shape and a signal-to-noise ratio for TOF MS implying a detection limit for isoprene of ≪10 ppt under the conditions used. Method conditions are shown in Table 10.