PlasmaQuant MS product family
Method optimization
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6.
Slightly adjust the voltages applied to ion optics to achieve the required sensitivity
for each isotope of interest.
When close to optimum, any further changes to the ion optic settings will typically
begin to bias the sensitivity towards the low-mass or high-mass element.
As this is done, monitor the oxide ratio and doubly-charged ratio to make sure they
all meet performance requirements (see Method optimization p. 75).
If the oxide ratio is too high, slightly adjust the sheath/nebulizer gas flow or the
peristaltic pump speed to reduce it.
Changes applied to the ion optics will have very little influence on the oxide ratio.
The main influencing factors on the proportion of oxides are the sheath gas
flow/auxiliary gas flow, the plasma conditions (RF power) and the pump speed.
7.
Click the [S
AVE
] button or select S
AVE
from the F
ILE
menu to save the parameters.
8.3
Automatic optimization
Included in the ASpect MS software are several auto-tuning routines, which allow the
optimization of the ion optics, based on the factory’s specifications. Using the auto-
tune functions will greatly simplify the operation of the PlasmaQuant MS and always
ensure it is operating at peak performance.
During an auto optimization, the results for each criterion and overall response can be
monitored visually. At the end of optimization, the best settings can be transferred
automatically to the Method of a current worksheet. Alternatively, the auto
optimization can be stopped at any time if the settings found are satisfactory, and
these settings are saved as the "best-so-far" settings.
Before starting the method optimization of the ion optics, prepare a 1 µg/L (1 ppb)
tuning solution, (containing Ba, Be, Ce, Co, In, Pb and Mg). The tuning solution is
required when using the Auto-Optimization feature in standard or high performance
mode. The ion optics auto-optimization routine in iCRC mode requires a solution of
5 µg/L (5 ppb) As, 20 µg/L (20 ppb) Sc and 20 µg/L (20 ppb) Y in 1 % HNO
3
(no HCl).
8.3.1
Copy and paste optimization settings
If possible, it is recommended to use "known well" settings. If there is an existing
worksheet that has settings that result in good sensitivity and stability, those settings
can be copied to begin the optimization process. If there are no worksheets to use, the
system setup worksheet or factory test records supplied with the instrument can be
used as initial settings.
For information on copy and paste, see section "Copy and paste optimization settings"