Zn/Mo/Ni low recoveries

Hi all, I am currently in the process of creating and validating a method for a soil digestion on a 7800. Most of what I have has been running fairly well, but a few elements have been giving me some issues with low recoveries. Zn, Mo, and Ni are all coming up just short of 90% recovery. For the most part they run 80-85%, but I do need it to run at least 90% for my initial QC check. I have played with both modes available to us currently (No gas/He). Any insight on the lower recoveries?

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  • Hi Ryan,

    It's best to run the Zn/Mo/Ni in He mode due to spectral interferences.

    please check several things. If recovery is low then it's almost impossible that spectral interference give the issue, where spectral interferences give positive errors. Most likely the efficiencies of the sample preparation isn't at the correct level due to acid type or temperature/ time selection. Or the selection of the correct Internal standard (ISTD) should be reconsidered. ISTD should be matching in Ionization potential and mass range. Hopefully this help you in the good direction.

    Maybe this article give some insight for the measurement:

    5990-5514EN.pdf (agilent.com)

Reply
  • Hi Ryan,

    It's best to run the Zn/Mo/Ni in He mode due to spectral interferences.

    please check several things. If recovery is low then it's almost impossible that spectral interference give the issue, where spectral interferences give positive errors. Most likely the efficiencies of the sample preparation isn't at the correct level due to acid type or temperature/ time selection. Or the selection of the correct Internal standard (ISTD) should be reconsidered. ISTD should be matching in Ionization potential and mass range. Hopefully this help you in the good direction.

    Maybe this article give some insight for the measurement:

    5990-5514EN.pdf (agilent.com)

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