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Resolution/Axis troubleshooting & He mode drift

taylordavidson

Hi everyone,

Recently, when we've been running the warm up procedure on our ICP-MS 7900, an error message appears next to Resolution/Axis.
It says that there is a potential interfering peak at m/z 6. We've cleaning every part possible (cones, lenses, torch etc) and changed tubing but still have no luck in getting rid of this. Could there be possible contamination somewhere or has anyone had this error message before and knows what it could mean?  We monitor masses 7, 89 and 205 during the start-up.


In addition to this, we've also been experiencing significant fluctuation/drift in analysis for He mode. Randomly in the middle of a batch, any elements and ISTD analysed under He mode drops in recovery significantly, then when I rerun the same sample immediately after, recovery comes back into spec and results are acceptable. Turning off the internal standard makes no difference to the results, so I don't think that's the issue. This is even happening with relatively easy/low matrix samples such as our rinses and QC samples. Anyone any advice on where to go from here or what's causing this disruption?

Thanks in advance
Taylor

  • +1

    Hi

    In ICPMS, sampling is very important as deposit will contaminate the sampling path.

    You are cleaning but still problem there. So replace tubing, nebulizer where high chances of deposit.

    Reagent should not be expired..

  • 0

    Hi Taylor,

    Did you discover an answer to your problem? We are experiencing nearly the same phenomenon, though in O2 mode rather than He mode. 

    We will suddenly lose 50% of our sensitivity on analytes and internal standard, together. It happens regardless of sample, and even in blank internal standard solution. Recoveries remain low for the rest of the day, but sensitivity is restored at the beginning of the next day's run.

    We've replaced our cones and tried swapping the nebulizer, these haven't helped.

    Cheers,

    Laura

  • 0

    If everything is fine in no gas mode, I would check the gas lines for any leak or the He filter might be saturated. In order to narrow down the issue, you can open an older batch and note down the counts for an internal standard in He mode. Compare the counts with the counts in your current batch. If you have much less sensitivity, you should certainly check your He line. If not, there might be an issue with the octopole. In that case you should contact your local Agilent team. This procedure applies also to any other gas mode. 

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