Disminución abrupta de abundancia

Por que razón puede haber bajado la abundancia de 900000 a 123000 en 2 dias, siendo que la fuente fue limpiada y el voltaje del electromultiplicador da 1857

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    Abrupt decline in abundance
    For what reason could the abundance have dropped from 900,000 to 123,000 in 2 days, since the source was cleaned, and the electron multiplier voltage gives 1857.
  • the abundance of ion 69. I rechecked the source and it doesn't look dirty. then I did an autotune it stopped on the width mass axis of the second quadrupole.
    Finally, after 2 or 3 more attempts, I ended up completing the autotune with an abundance of ion 69 of 1,200,000.
    It is strange how this abundance fluctuates, since the areas in the chromatograms remain practically constant for the analytes that I run in the equipment. Could it be an indication that something is about to fail?
  • Which MS model is this? 7000 or 7010?

    With SQ instruments we tune with a static base peak abundance target of 500,000 and a dynamic detector EMV/Gain (ie, the detector will be adjusted to achieve 500,000 counts of either 69 or 219.)

    With TQ instruments we use a static detector gain of 1.0 on 7000 and 0.1 on 7010 instruments. This means that the detector amplification is static, and the observed abundance of PFTBA will by dynamic depending on the condition of the instrument.

    It is normal to see some change in abundance from tune to tune. If I got an abundance of 6 million 69 one day and then a week later I tuned and got either 7 million or 4 million I would not think that is a problem. And as you say, despite these changes in abundance your analysis method analytes have consistent abundance. 

    However, if the tuning abundances drop significantly (like 123,000 counts), or if the abundances of your analytes in the analytical method drop significantly, it is a sign that maintenance may be needed (most likely of the source.) You've already done this. If you continue to have tuning errors indicating an issue with MS2 mass calibration I would recommend having a service engineer come and evaluate the instrument.

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