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Agilent 7500 ICP-MS ChemStation Operator’s Manual
Tuning
Tuning the Detector
An electron multiplier (EM) is used as the detector. There are 2 modes for detecting
signals and it is possible to measure samples with concentrations ranging from sub
ppt up to hundreds of ppm.
• Pulse counting mode
Pulse mode is selected automatically when the counts are lower than 1Mcps. If
using the normal torch, this mode covers the range from sub ppt to 100 ppb.
•Analog mode
Analog mode is selected automatically when the range of the counts are from
approximately 1Mcps to the corresponding signal of 4Gcps. If using the normal
torch, this mode covers the range from 100 ppb to hundreds of ppm.
When data acquisition starts, pulse mode at low concentration range and analog
mode at high concentration range are automatically switched. When the signal is too
high, the mass number is skipped to protect the detector.
Each EM parameter is adjusted in autotune, you must not adjust the voltages
manually. This will effect the gain and correlation between pulse and analog counts.
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