Prevention Of Em Deterioration - Agilent Technologies 7500 ICP-MS Operator's Manual

Agilent 7500 ICP-MS ChemStation Operator's Manual
Tuning

Prevention of EM deterioration

When higher signals are analyzed for a long time with very high sensitivity, the EM
may deteriorate fast. EM deterioration causes drift of the signal and the lifetime of
the EM may be shortened. The following methods will minimize EM deterioration:
• Set suitable integration time
Shorten the integration time according to the suitable setting required for the
production of reproducible data. The following table shows the recommended
value of integration time for the prevention of EM deterioration. Please refer to it
and set the integration time for each mass.
Recommended Value for Integration Time
The Standard of
concentration *
< a few 10 ppb
10 ppb to
approx.100ppb
> approx.100ppb
These values are only for reference, so please set longer integration times for
your application, if necessary. For more information regarding the settings for
integration time, please refer to Chapter 5, "Creating a method" and the Applica-
tion Handbook.
• Decrease the intensity
When the concentration of signals that you want to analyze is large, high sensitiv-
ity is not required. It is recommended to decrease the sensitivity. If you want to
decrease the intensity, adjust the ion lens voltage (not the EM voltage). To adjust
the ion lens voltage, see "Tuning for Sensitivity" in this chapter.
4-92
Counts Integration Time
0 to 500Kcps
500kcps to 1Mcps
1Mcps to 4Gcps
Detector Mode
per Point
> 0.1sec Pulse
0.01sec Pulse
0.01sec Analog
* the sensitivity is 10,000 cps/ppb