Agilent Technologies 7500 ICP-MS Operator's Manual page 114

10 Check the background level
N O T E
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Agilent 7500 ICP-MS ChemStation Operator's Manual
Tuning
sensitivity
ArO
Behavior of Co, ArH and ArO
If the tuning solution contains impurities and it is difficult to check the background
of 39amu(ArH) or 56amu(ArO). Use fresh ultra pure water and check if the signal is
decreased. The following are standard levels:
39amu(ArH)--less than 1/10
56amu(ArO)--less than 1/100
Easily, there may Fe and K contamination from the environment. Even in the clean
room, there is a possibility of contamination if samples are exposed to wind;
therefore, use fresh ultra pure water.
Example
Element
Co (59 amu)
ArO (56 amu)
Compared to the normal plasma, the cool plasma reacts more sensitively to the matrix
effect. Therefore, it is recommended to use the matrix matched tuning solution when
analyzing high matrix samples with the ShieldTorch system.
4-38
Co
ArH
increasing carrier gas flow
∼
1/50 of 59 amu signal (Co 10 ppb).
∼
1/500 of 59amu signal (Co 10 ppb).
Count/ 1 ppb (Integ.: 0.1 sec)
1000 ~ 3000
>
1
< Signal (59) x
100