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iCAP Customer Familiarisation Manual
Page 61 of 72
This document is part numbered 849940090071
9 Analytical Problems Hints and Tips
9.1 Poor Precision
A quick test should be run to determine if the poor analytical results are matrix
related.
A 10 ppm solution of a few common elements such as Cu, Mn, Ba, Cd, Zn and
Fe should be put together and a metho
default conditions.
After standardisation, the standard should read back, on the iCAP for example,
with a precision of typically 0.2 to 0.5 percent (with a 10 second integration
time). If the precision obtained is substantially greater than this try Torch
alignment then go o
If the instrument meets these specifications then the sample matrix itself is
suspect.
Possibly modifying plasma parameters such as power will help the situation.
Poor precision generally relates to
problems in the sample introduction
system.
First check to ensure that the
nebuliser pressure or flow is set
correctly by aspirating a 1000 ppm
Yttrium solution (Sodium will also
work if no Yttrium is available).
Check to ensure that the centre
orange "bullet" is even with or slightly
above the top of the Radial torch. If
not, adjust the nebuliser pressure up
or down until the "bullet" looks correct.
At this point the nebuliser
should be approximately 0.15 mPa
(150kPa/25psi) for aqueous solutions.
If the pressure is substantially higher,
the nebuliser orifice is generally to
blame and should be cleaned.
Pooling and dripping in the spray
chamber can also cause many
precision problems. You may be able
to see this visually using the Y test
described above.
If the Yttrium "bullet" is
and down inside the plasma, it is
iCAP Customer Familiarisation Manual
This document is part numbered 849940090071
Analytical Problems Hints and Tips
Poor Precision
quick test should be run to determine if the poor analytical results are matrix
A 10 ppm solution of a few common elements such as Cu, Mn, Ba, Cd, Zn and
Fe should be put together and a method made using the primary lines and
default conditions.
After standardisation, the standard should read back, on the iCAP for example,
with a precision of typically 0.2 to 0.5 percent (with a 10 second integration
time). If the precision obtained is substantially greater than this try Torch
alignment then go on to trouble-shoot further if the problem remains.
If the instrument meets these specifications then the sample matrix itself is
Possibly modifying plasma parameters such as power will help the situation.
Poor precision generally relates to
lems in the sample introduction
First check to ensure that the
nebuliser pressure or flow is set
correctly by aspirating a 1000 ppm
Yttrium solution (Sodium will also
work if no Yttrium is available).
Check to ensure that the centre
orange "bullet" is even with or slightly
above the top of the Radial torch. If
not, adjust the nebuliser pressure up
or down until the "bullet" looks correct.
nebuliser pressure
should be approximately 0.15 mPa
for aqueous solutions.
If the pressure is substantially higher,
the nebuliser orifice is generally to
blame and should be cleaned.
Pooling and dripping in the spray
chamber can also cause many
ecision problems. You may be able
to see this visually using the Y test
If the Yttrium "bullet" is bouncing up
and down inside the plasma, it is
Version 1.02
quick test should be run to determine if the poor analytical results are matrix
A 10 ppm solution of a few common elements such as Cu, Mn, Ba, Cd, Zn and
d made using the primary lines and
After standardisation, the standard should read back, on the iCAP for example,
with a precision of typically 0.2 to 0.5 percent (with a 10 second integration
time). If the precision obtained is substantially greater than this try Torch
shoot further if the problem remains.
If the instrument meets these specifications then the sample matrix itself is
Possibly modifying plasma parameters such as power will help the situation.