High Vacuum Pressure In Ci Mode - Agilent Technologies 7200 Operation Manual

4
Operating in Chemical Ionization (CI) Mode

High Vacuum Pressure in CI Mode

The largest influences on operating pressure in CI mode are the reagent and
collision cell gas flows.
flows, depending upon the collision cell gas flowrate. Familiarize yourself with
the measurements on your system under operating conditions and watch for
changes that may indicate a vacuum or gas flow problem. Measurements will
vary by as much as 30% from one MS to the next.
Analyzer vacuum with reagent gas flowing
Note that the mass flow controller (MFC) is calibrated for methane and the
vacuum gauge is calibrated for nitrogen, so these measurements are not
accurate, but are intended as a guide to typical observed readings
They were taken with the following set of conditions. Note that these are
typical PCI temperatures:
Source temperature
Quad temperature
Interface temperature
Inlet
Oven
Helium carrier gas flow
Table 6 Typical analyzer vacuum with reagent gas flow
MFC (%) Rough Pump
(mTorr)
0 1.36e+02
10 1.36+02
15 1.43+02
20 1.5+02
25 1.57+02
30 1.63+02
35 1.69+02
40 1.74+02
62
Collision cell gas flow on
N = 1.5 mL/min
2
Quadrupole
(Torr)
3.62e-05
3.62e-05
3.66e-05
3.71e-05
3.73e-05
3.77e-05
3.81e-05
3.83e-05
Table 6 lists typical pressures for various reagent gas
230 °C
150 °C
280 °C
250 °C
100 °C
1 mL/min
Flight Tube Rough Pump
(Torr) (mTorr)
3.35e-07 9.13e+01
3.37e-07 1.14e+01
3.37e-07 1.23e+01
3.39e-07 1.31e+01
3.41e-07 1.39e+01
3.41e-07 1.46e+01
3.41e-07 1.52e+01
3.43e-07 1.58e+01
7200 Accurate-Mass QTOF Operation Manual
Collision cell gas flow off
N = 0 mL/min
2
Quadrupole
(Torr)
5.98e-07
1.27e-06
1.62e-06
1.96e-06
2.32e-06
2.64e-06
3.00e-06
3.34e-06
(Table 6).
Flight Tube
(Torr)
1.64e-07
1.65e-07
1.67e-07
1.67e-07
1.70e-07
1.71e-07
1.71e-07
1.72e-07