Are you using the same view for both old and new methods? Alkali metals (Na
& K too) should be measured radially. Excitation of these easily ionizable
elements are very dependent on plasma temperatures and the temperature
gradient across the plasma (radial) are much less than the temperature
gradient along the plasma axis (axial). If you have to use the axial view,
an ionization buffer is recommended. If you are using the radial view, check
the sample stabilization time - it may need a few extra seconds to properly
set the pre-shot times. This is assuming you are using auto-integration and
not setting these manually.
How are the intensities of the other elements? Are they also higher than
those from the old methods?
ICPAA Expertise Inc
From: PLASMACHEM-L: Analytical Chem.(ICP's, DCP's, MIP's).
[mailto:[log in to unmask]] On Behalf Of Nelles, Bob
Sent: January 13, 2010 2:03 PM
To: [log in to unmask]
Subject: Saturated Li Counts
Greetings Plasma Chemist,
I am having an event where my Li wavelength(670.784)is reported as
saturated in my calibrant. This "error" does not happen everytime I
calibrate the PE 3000 DV, but it does happen the majority of time, about
eight out of ten. When Li is successfully calibrated it generates
approximately 14,000,000 counts. This intensity is higher than any other
element in the calibration soup. I looked at data that was a year old and
the counts for LI were 5,000,000 counts. We checked the concentration of
our Li calibrant on the MS and it was within the acceptable range for 1.0
ppm. Our instrument is fifteen years old. This started happening after I
had to rebuild the method after loosing files, so the odds of operator error
are high. I have looked at the delay times in our documentation and they
are the same as before the data loss.
Thankyou in advance for your time and advice.
1000 NE Circle Blvd.
Corvallis, Or 97330