Low sensitiviy and change in cps through time ICP-MS 8900


From a year till now, every time we measure, whether in LA-ICP-MS or in liquid mode, sensitivity is not good.

Furthermore, relationship between masses differ a lot through time (like, 3 or 4 hours).

Agilent Argentina does not provide useful help and takes months to respond.

We cleaned lenses, torch, nebulizer and the cones seem in good shape.

Only thing we didn't touch is the reaction cell.

Maybe something of the tuning could improve, or may this be hardware realted?

This is the last standard tune (the one that runs at starting plasma, we do this every week using 1 ppb of masses Li, Mg, Ce, Co, Y, Tl)

And this is the specific tuning for solution 1 ppb of same elements of before plus 1 ppb U, Th, Pb (also note that uses He mode)

Any lead could be useful, thanks.



  • Hi Lisandro,

    The first thing that pops out is that you have voltage on Extract lens 1.  With the x-lens it is typically set to zero.  In the first report (looks like aqueous) the counts for mid and high mass are great, but low mass is below spec.  Check that changes in omega lens and omega bias have inverse affects on low and high mass.  Li7 should go up as Tl205 goes down when changing those voltages.  If not, run the lens shortage test.  If it passes, check the lens contacts on the interface.

  • Hi Tom.

    Sorry for the delay, and thanks for the answer.

    Shortage test is allright, and also the contacts are in good form and shape.

    I don't know about the voltage on Extraction lens. It's been always around that value, even then counts where good some time ago.

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