7800 ICP-MS Tuning

Hi all,

I have several questions about this tuning report, picture attached. The doubly charged percentage is too high, how do I improve this, what is considered acceptable or normal?

Also the peaks don't look too sharp, they are wider than what I am used to seeing, how do I improve the peak symmetry, the peak for 205 looks very jagged at the top, how can I resolve this peak better. 

I would greatly appreciate any feedback you can provide. 

Thank you!

  • Just a very simple thing.

    Do you maybe use Ge as internal standard? I do, and one time I also had a very high double charged value because I had contamination during the tune.

  • Hi, 

    as mentioned before it looks like, you still have connected the internal std. (the Li6 signal is indicating this).

    1. Exchange the ISTD to 1% HNO3

    2. Fill up some fresh tuning solution to get rid of the Pb contamination (206)

    The doubly charged rate is calculated with the signal ratio of 70 / 140. If you have a "real" signal on the 70, mostly from Zn70, Ge70 or CLCL, this will affect your Ce++ rate.

    Regarding the peak shape: This is not looking bad at all.

    If your instrument is maintenanced by agilent, ask your service representative if he could improve this.



  • Hi Chris,

    Thank you for a thorough response! I always remove the ISTD and replace it with 1% HNO3 before tuning, however I think Lithium 6 was not rinsing out, so I replaced the rinse solution with 5% HNO3. I was able to get the Li6 down considerably, but Pb206 is still there, the tuning report I linked was made using a fresh 1ppb tune solution. 

    The following elements are in our ISTD solution: Li6, Sc, Ge, Y, Rh, In, Tb, Lu, Ho. Bi. If I were to thoroughly rinse the system before performing the tune do you anticipate that the doubly charged ratios will improve (rinsing Ge out)?


  • Hi,

    rinsing with a higher concentration of HNO3 sounds like a plan Slight smile

    you could try to sonicate the T-Piece where the istd is connected. Often this is a source for contamination. 
    Anyway the Pb is not a problem in this low concentration. And your main concern was the Ce++ rate which is definitely affected by Ge. 



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