Agilent Technologies 7500 ICP-MS Operator's Manual page 97

Agilent 7500 ICP-MS ChemStation Operator's Manual
Tuning
potentials of polyatomic ions are relatively high, probably higher than 10 eV and
similar to that of Cl.
100
10
1
0.1
0.01
0.001
0.0001
0.00001
0.000001
0.0000001
4,500
Ionization Efficiency of Elements as a Function of the Electron Temperature
In conclusion, by using the combination of the ShieldTorch system and cool plasma
conditions, polyatomic ions such as ArH, ArC, and ArO can be drastically reduced
while analytes such as Li, Na, Mg, K, Ca, Cr, and Fe are still ionized efficiently.
5,000 5,500 6,000
Electron Temperature (K)
6,500 7,000 7,500
Li
Be
Mg
Cl
Ar
Fe
As
4-21