Each Parameter's Function - Agilent Technologies 7500 ICP-MS Operator's Manual

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Agilent 7500 ICP-MS ChemStation Operator's Manual
Tuning

Each Parameter's Function

The working of each parameter used for sensitivity adjustment is described below.
The Agilent 7500ce has three modes: Standard Mode, which does not use a reaction
gas, Reaction Mode, which uses hydrogen (H
gas. For information on sensitivity adjustment in each mode, refer to "Information on
Sensitivity Adjustment" on page 4-46.
Plasma Condition
• RF Power
It controls the RF power supplied to the load coil. A higher RF power increases
the sensitivity and reduces oxide and doubly charged ions. However, the
sensitivity of lighter masses may be decreased when the RF power is too high.
• RF Matching
Adjusts reflected RF returned from the load coil.
To reduce the reflected power, use of the automatic adjustment function is
recommended. To use the automatic adjustment function, select Tune>>RF
Matching on the Tuning window, and then follow the displayed dialog box.
If you adjust the RF Matching manually, use only the scroll arrows to change this
value. If you click on the scroll bar itself, the instrument will turn off the plasma.
Adjust until the RF reflected power meter reads as low as possible. Standard value
for RF matching is approximately 1.6 to 2.0 V.
• Smpl Depth
It controls the distance between the edge of the load coil and the tip of the
sampling cone. A shorter sampling depth increases sensitivity, but the oxide level
increases as well.
• Torch-H, Torch-V
It adjusts the torch position. The Torch-H and Torch-V parameters measure the
horizontal and vertical movement of the torch relative to the interface. Adjust to
get the highest sensitivity for all masses. When the sampling depth is changed,
adjustment of the Torch-H/V will be required. If these parameters are changed
using the software scroll bar, the plasma may turn off. Use only the scroll arrows.
• Carrier Gas
It controls the nebulization efficiency of a sample and the sample uptake rate
when self-aspiration is applied. In general, a gas flow of 0.9 L/min when using
the Micro Mist Nebulizer.
) gas or helium (He) gas as a reaction
2
4-43