Examining Selectivity using High Resolution Extracted Ion Current Chromatograms (EICC)
JEOL MS Data Sheet MS Tips No.130
Samples and Measuring Conditions
|KC-500 (0.1 ppm), transformer oil (diluted 10000 times)|
|Sample inlet: Splitless, 280°C
Column: DB-5, 10 m x 0.18 mm, 0.18 μm
He flow rate: 0.5 ml/min (fixed flow rate)
Oven: 50°C (2 min) → 60°C/min → 280°C (2 min)
|MS: JMS-T100GC AccuTOF GC
Ionization mode: EI+ (ionization voltage: 70 eV, current: 300 μA)
Mass range: m/z 30 to 550
Recording interval: 0.1 s (10 Hz)
Temperature: Ion source: 280°C, GC-ITF: 280°C
Result and Discussion
The window width for the EICC generation was varied to see if the chromatographic effect of the background interferences can be eliminated. Figure 1 shows the EICCs generated under low resolution (top) and high resolution (bottom) conditions. “Low resolution” and “high resolution” do not refer to the resolving power of the instrument, but instead refer to the different window widths used for the m/z 352.88 EICCs. The mass resolution levels calculated with the different window widths are shown in Figure 1. The actual resolution for the data acquired by the AccuTOF GC during these sample measurements was R≧5000 @ m/z 293. As Figure 1 shows, the low resolution EICC (m/z 352.88049 ± 0.5, analogous to a quadrupole MS analysis) showed a wide, unresolved sample envelope that was caused by the transformer oil. Meanwhile, the high resolution EICC (m/z 352.88049 ± 0.05) eliminated the effect of the oil background, and extracted only the peaks for the penta-chlorinated PCBs.
These results demonstrate that the AccuTOF GC, a high resolution GC-TOFMS system, is a powerful tool for analyzing complex real-world samples that contain high levels of interfering impurities.
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