Agilent Technologies 7500 ICP-MS Operator's Manual page 112

Agilent 7500 ICP-MS ChemStation Operator's Manual
Tuning
Typical values for the ShieldTorch (Cool plasma)
Tuning parameter Typical
RF Power (W)
Smpl Depth (mm)
Torch-H (mm)
Torch-V (mm)
Carrier Gas (L/min)
Makeup Gas (L/min)
PeriPump 1 (rps)
Extract 1 (V)
Extract 2 (V)
Einzel 1,3 (V)
Einzel 2 (V)
Omega Bias (V)
Omega (+) (V)
Omega (-) (V)
4-36
Range
∼
900
600 1000
∼
13
10 20
- -
∼
1.0
0.8 1.3
∼
0.6
0 1.0
∼
0.1
0.10 0.20
∼
-50
-100 -20
∼
-10
-100 -10
∼
-100
-200 -100
∼
0
0 15
∼
-30
-100 -25
∼
0
0 30
∼
0
-30 0
Adjust the RF power lower than the standard torch.While
monitoring the RF reflection power from the Tuning window,
make the RF power lower from the normal plasma (1200-1400
W) to 900 W.
If the RF reflection power increases, adjust the RF matching to
prevent the RF reflection power from increasing.
In the case of 600W, plasma may turn out. If this happens, set it
higher than 800W and turn on the plasma again.
Keep it apart from the standard torch position.
Changing the Sampling depth may slip the torch axis, it is
necessary to adjust frequently.
The supply pressure of the Ar gas restricts the carrier gas flow
rate. Make up the loss by introducing the Makeup gas.
For the standard torch (injector internal diameter is 2.5 mm), the
standard value is about 1.6 L/min including the carrier gas.
In the case of using a smaller injector torch, the best flow rate
will be lower than 1.6 L/min. (about 1.2L/min if the injector's
internal diameter is about 1.5mm).
If the Makeup gas flow rate is increased, the signals of ArO
(56amu) will be decreased.
To lower the plasma temperature, increase the number of pump
rotation.
Even if the value of the Einzel lens is decreased, the background
may hardly be increased and only sensitivity may be increased,
compared to that of the standard torch.
If this value is lowered, sensitivity may be increased.
Even if the value of the Omega lens is decreased, the
background may hardly be increased and only sensitivity may
be increased, compared to that of the standard torch.
Note