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Counts going down ICP-MS 8900 during 2 hours test

lisandrom91

Hi everyone.

We've been experiencing some trouble with our equipment, as detailed in:  Low sensitiviy and change in cps through time ICP-MS 8900 

We already polished and cleaned lenses, cleaned introduction system, and the sampling and skimer look alright. We also opened the vacuum chamber and closed it (without any further modifications).

Now remains a different but pre-existan problem The last 2 reports had decent sensitivity but CPS go down all the time. This are the results of a test indicated by Agilent:

Solution is 1 ppb tuning, and is being pumped all the time without an autosampler, like this:

Any ideas, suggestions? Is it a normal behaviour? I don't think so.

Thanks

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  • 0 in reply to lisandrom91

    There is a new grounding piece New PN for Pin GND support part (PN change from G3280-20577 to G8400-67065) to solve the trouble of electro-static charge related signal instability.  Also, it looks like you have RSD issue in the performance you show up.  The sensitivity line shows a problem with either peri pump tubing tension or old tubing.  Also, the performance shows up nice counts level.  But your analysis shows low count level for 1ppb tune solution in MSMS.  You can post your tune report for this analysis.  Also, at last.  Make sure the ventilation does not change during analysis and temperature is stable into the lab Max 5C variation in whole day and less then 2C/hour.   

    Sampling cone opening 1mm good shape.

    Skimmer cones 0.45mm good shape

    Wrong in there and the beam of ions will be deflected causing the low sensitivity.

    When you open the vacuum chamber you need to wait pump down overnight.  It's always a good idea to purge with argon inside the vacuum chamber before closing the lid.  

  • 0 in reply to ulrichntaniel

    Hi, thanks for the answer and sorry for the delay, I haven't seen this notification!

    Solution of the tuning is the same of the test. (1 ppb Li, Mg, Y, Ce, Tl, Co) Ventilation is not changing and temperature is stable in the laboratory room.

    Sampling and skimmer cone both have the diameter respected, but the shape of skimmer isn't round anymore, it has a little defect:

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