Ion Lenses - Agilent Technologies 7500 ICP-MS Operator's Manual

Agilent 7500 ICP-MS ChemStation Operator's Manual
Tuning

Ion lenses

• Extraction 1 & 2
It extracts ions from the plasma to accelerate them toward the Einzel lens. Adjust
to get enough sensitivity for all masses. This is lens that needs the most
frequently adjusted everyday.
In order to get maximum sensitivity, adjust between 0 V and 6 V. An element of
low mass gets maximum sensitivity at low voltage. On the other hand, an
element of high mass gets maximum sensitivity at high voltage. Therefore, select
the appropriate voltage. Even with the voltage around -100V, high sensitivity can
be obtained. However, the background of polyatomic ions may be high in the
reaction mode (H mode or He mode)
2
• Einzel 1,3
It focuses the ion beam from the extraction lens. A typical value is -80V. If the
voltage becomes lower, sensitivity will go up, but the off-mass background will
also be high.
• Einzel 2
It focuses the ion beam from the extraction lens. An element of low mass number
gets maximum sensitivity at low voltage. On the other hand, an element of high
mass number gets maximum sensitivity at high voltage. Therefore, set a value to
get enough sensitivity for all masses.
• Omega Bias
Provides the same potential at the entrance and exit of the Omega lens block. It
must be used at voltages more positive than -40V. The more negative voltage, the
higher the sensitivity, but the background might increase.
• Omega (+), Omega(-)
Separating the ions from photon and introduce the ions to the Q-pole. Adjusts to
get good sensitivity for all masses.
• QP Focus
Decelerates and focuses the lenses and introduces the ions to the Q-pole. Adjusts
to get good sensitivity for all masses.
• Plate Bias
Re-focuses the ion beam. A typical value is 0 V without the ShieldTorch system.
It may be used several voltage when the peak shape and resolution are not good.
This voltage should be the same as the QP Bias to avoid higher background.
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