ICP-MS 7900, mercury dilution false concentration

Hello Everyone
I have an issue with ICP-MS 7900 on mercury analysis. If we run 1:1 dilution after digestion the results are OK but when we need to analyze the further dilutions I get high concentration of mercury and amazingly the RSDs are not high to say it's a false pulse. Does any body had a similar experience? Please let me know if you needed further information.
Thank you

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  • Hi

    Thanks a lot, I'll try the application.

  • Hello again

    I read the app you sent it to me and it's almost the same as our procedure.

    Well let me explain my problem in another way! I don't have any issue with calibration or mercury stability. The system is good from the beginning to the end of the batch. As long as I run samples after digestion with 1:1 dilution everything goes well and mercury is not detected, since our samples are mostly cosmetics sometimes I can't inject direct dilution because of viscosity or color, so I run a dilution of 1:10 or further one. Here my problem appears, normally if the solution gets diluted we shouldn't see either any value for Hg or if there is a concentration then the RSDs are supposed to be way much high to interpret that this value is not real. But I get detected values with a low RSD. I'm looking for the reason to justify those are not real values!

    Thanks again for your help

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