Discriminator; Em Voltage (Analog Hv, Pulse Hv) - Agilent Technologies 7500 ICP-MS Operator's Manual

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Agilent 7500 ICP-MS ChemStation Operator's Manual
Tuning

Discriminator

The discriminator is a threshold for determining the difference between general
electrical noise from power supplies etc. and analyte signal. If it is set too low, the
noise becomes high. If it is set too high, it cuts not only the noise, but also decreases
the sensitivity. Only use autotune to adjust the discriminator.

EM Voltage (Analog HV, Pulse HV)

The ions are converted into secondary electrons and the output of the signal is an
amplification of these electrons. A higher EM voltage gives higher sensitivity, but
there is a possibility that the EM deteriorates faster due to excessive signals. Only
use autotune to adjust the EM voltage (do not adjust manually).
Tuning of the EM voltage will be required frequently when you analyze samples with
a wide concentration range where both the pulse and analog modes are used., it is
required every day when higher signals are analyzed for a long time the EM
deteriorates faster.
You must do the P/A factor adjustment after tuning the EM voltage. For information
about P/A factor settings, see "Setting P/A Factors".
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