Methanol as a solvent for ICP-OES

I am completing some sample preparations by SPE (for chromatography analysis) and I want to investigate breakthrough metal concentration for the eluted sample by analysis on our ICP-OES.  The SPE elute solution is 5% ammonia in 20% water and 75% methanol.  This solution will be diluted in water/nitric acid (x10) before analysis on the ICP.  Is it OK is my ICP sample contains approximately 7% methanol and 0.5% ammonia?  Typically our samples are pure aqueous/nitric with no methanol.

  • Hi,

    I don't expect much problems with the icp-oes measurement. However if doubts are about the chemical stability of the measured elements it's maybe better to dilute with at least 2-3% HNO3 solution where then the pH going below 7

    Be aware that carbon based spectral interference are highly present in the spectra and check this with confirmation wavelengths.


  • Hi Edgar, 

    Thank you so much for getting back to me. 

    Are there any safety concerns with adding HNO3 to an aqueous/methanol solution of approximately 90/10?

    This has been raised as a potential safety issue.  As we don’t have any experience with this, I would appreciate any advice about additional safety protocols with this.  Or is this a common sample prep method where the water concentration is high enough to quench any rapid reaction?



  • Hi Nathalie,

    yes, your right. Direct transfer of concentrated HNO3 to concentrated alcohol give an big exothermic reaction. 

    If the alcohol or HNO3 is buffered with water, like the 90/10 from your explanation then the reaction goes slower (or doesn't start?) 

    From my experience with HNO3 addition in wine or light spirits no big exothermic reaction started, only a bit warm. But always transfer the HNO3 in the safety cabinet and wait for a time and feel if the tube or beaker is (still) hot. If not then the reaction is stopped or negligible.

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