Poor Accuracy/Feedback; Poor Detection Limits - Thermo Scientific iCAP 7000 Series Manual

iCAP Customer Familiarisation Manual iCAP Customer Familiarisation Manual

9.2 Poor accuracy/feedback

Poor accuracy/feedback
First we should define accuracy as reproducing the standard value once standardised First we should define accuracy as reproducing the standard value once standardised First we should define accuracy as reproducing the standard value once standardised
Proceed by making a standard as in the previous section (10 ppm Cu, Mn, Cd, Zn, Fe) Proceed by making a standard as in the previous section (10 ppm Cu, Mn, Cd, Zn, Fe) Proceed by making a standard as in the previous section (10 ppm Cu, Mn, Cd, Zn, Fe)
and using this as the test solution. Remember we are not defining accuracy for this test and using this as the test solution. Remember we are not defining accuracy for this tes and using this as the test solution. Remember we are not defining accuracy for this tes
as the ability to read a 1 or 100 ppm standard after standardising on the 10 ppm. Most of as the ability to read a 1 or 100 ppm standard after standardising on the 10 ppm. Most of as the ability to read a 1 or 100 ppm standard after standardising on the 10 ppm. Most of
the time that problem is operator-related. As far as we are concerned at this point we the time that problem is operator
have only one standard to test with. If this simple standard will not repeat back for all have only one standard to test with. If this simple standard will not repeat
elements, check the pump winding first. Replace it if it is used or collapsed. elements, check the pump winding first. Replace it if it is used or collapsed. elements, check the pump winding first. Replace it if it is used or collapsed.
Note: Pump windings typically last only a couple of days Note: Pump windings typically last only a couple of days
Check the method to see if a fast pump rate is used for the flush period. If it is, then Check the method to see if a fast pump rate is used for the flush period. If it is, then Check the method to see if a fast pump rate is used for the flush period. If it is, then
make the flush pump rate the same as the analysis rate and try it again. Inaccuracy h pump rate the same as the analysis rate and try it again. Inaccuracy h pump rate the same as the analysis rate and try it again. Inaccuracy
can sometimes be traced to the inability of the pump tubing to recover its shape can sometimes be traced to the inability of the pump tubing to recover its shape can sometimes be traced to the inability of the pump tubing to recover its shape
after being stretched. after being stretched.
Check the flush time for adequate rinse time. A 30-second rinse time is adequate Check the flush time for adequate rinse time. A 30
most cases but not if a slow pump rate is being used or if a very long piece of tubing most cases but not if a slow pump rate is being used or if a very long piece of tubing most cases but not if a slow pump rate is being used or if a very long piece of tubing
is used (as with the autosampler probe). is used (as with the autosampler probe).
9.3 Poor detection detection limits
This problem can be also related to This problem can be also related to
the poor precision problem discussed
earlier and is usually solv earlier and is usually solved by
approaching it as such. However, if approaching it as such. However, if
the loss of intensities is especially the loss of intensities is especially
pronounced at lower wavelengths it pronounced at lower wavelengths it
may be due to a dirty window may be due to a dirty window
mounted in the Purged Optical Path. mounted in the Purged Optical Path.
UV burn or a dirty mirror is UV burn or a dirty mirror is
characterised by a long term decline characterised by a long term decline
(six months or longer) of intensities. s or longer) of intensities.
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related. As far as we are concerned at this point we
problem discussed
This document is part numbered 849940090071 This document is part numbered 849940090071
back for all
.
second rinse time is adequate in
Version 1.02