Analysis of trace metal Cadmium in > 99% Molybdenum sample using ICP-MS

The main and obvious issue with this analysis is interference due MoO being the same mass as Cd.

Even using a DRC gas doesn't help much.

 

using an ICP-MS/MS (Triple quad) will definitely eliminate this issue but I don't have that option.

Let me know your thoughts.

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  • Hi ,

     

    I'd like some help understanding your question a little. Using the theoretical mass calculator here (http://www.chemcalc.org/), we find the following masses for the substances in which you're interested:

    • MoO: MW = 111.936997, EM = 113.90032
    • Cd: MW = 112.411552, EM = 113.90336

     

    MoOCd

     

    Comparing the theoretical spectra, it looks like you'd expect different peak distributions for each substance, even though you'd get highly similar accurate masses for the dominant isotopic compositions. The substantial peak at ~107.9 for MoO looks like it could be an easily identifiable distinguishing feature.

     

    What do you think? I'm not at all experienced in ICP-MS personally, but it seems like this would be a reasonable way of distinguishing the two without an MS that had super-resolution. Maybe if you had a mix of MoO and Cd you you determine the relative concentrations based on the relative intensities of the ~114 and ~108 peaks?

     

    Thanks. - Josh

Reply
  • Hi ,

     

    I'd like some help understanding your question a little. Using the theoretical mass calculator here (http://www.chemcalc.org/), we find the following masses for the substances in which you're interested:

    • MoO: MW = 111.936997, EM = 113.90032
    • Cd: MW = 112.411552, EM = 113.90336

     

    MoOCd

     

    Comparing the theoretical spectra, it looks like you'd expect different peak distributions for each substance, even though you'd get highly similar accurate masses for the dominant isotopic compositions. The substantial peak at ~107.9 for MoO looks like it could be an easily identifiable distinguishing feature.

     

    What do you think? I'm not at all experienced in ICP-MS personally, but it seems like this would be a reasonable way of distinguishing the two without an MS that had super-resolution. Maybe if you had a mix of MoO and Cd you you determine the relative concentrations based on the relative intensities of the ~114 and ~108 peaks?

     

    Thanks. - Josh

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