Agilent Technologies 7500 ICP-MS Operator's Manual page 145

Agilent 7500 ICP-MS ChemStation Operator's Manual
Tuning
• QP Bias
It controls the speed of ions when an element ion passes through the Q-Pole and
prevents polyatomic ions of low energy from passing. When peak shape and
resolution are not good, adjust it up to -2 V.
QP bias needs to be more positive than the OctP bias by the value shown as
below:
• In standard mode: 2 to 4 V (Block polyatomic ions produced from the residual
gas in the ion lens chamber.)
• In reaction mode: 1 to 2 V (Block polyatomic ions produced from the residual
gas in the ion lens chamber and the Ar-related polyatomic ions, which lost
energy by reaction. If the QP Bias is set to a high voltage, the sensitivity will
also decrease.)
Reaction Cell
• Reaction Mode
Switch between standard mode, cool mode and reaction mode. When a check
box is ON, it is in reaction mode and when a check box is OFF, it's in standard
mode, cool mode
• H Gas
2
Adjust the flow rate of hydrogen gas (H
the flow rate of H
2
the background. Adjust the flow rate in order to make the background low
enough and to get the necessary level of sensitivity.
• He Gas
Adjust the flow rate of helium gas (He) used as the reaction gas. The higher the
flow rate of He gas, the lower the sensitivity of a sample and the intensity of the
background. Adjust the flow rate in order to make the background low enough
and to get the necessary level of sensitivity.
• Optional Gas (option)
On the Agilent 7500cs, if an optional gas line is added other than H
gas, another type of gas can be introduced.
) used as the reaction gas. The higher
2
gas, the lower the sensitivity of a sample and the intensity of
gas and He
2
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